This super moist dark chocolate mousse cake combines unsweetened natural cocoa powder and dark cocoa powder for an extra rich flavor. Fill the cake with a simplified chocolate mousse and cover the whole dessert with semi-sweet chocolate ganache. If needed, you can prepare the ganache and mousse ahead of time.
My s’mores chocolate mousse inspired me to play around in the kitchen the other week. I’ve always loved chocolate mousse, back to my childhood when my mom served it as an easy (yet totally elegant) dessert on the holiday table. Chocolate mousse is simple divinity in its own right, but when paired with chocolate cake, it’s downright decadent.
I made this chocolate mousse cake for my husband Kevin’s birthday. This cake basically demands a huge gathering because—trust me—you don’t want to be left alone with its temptation. It WILL call out your name each time you open the refrigerator.
Taunting you.
3 Parts to Dark Chocolate Mousse Cake
Let’s break down each component of this intensely rich cake:
- Dark Chocolate Cake: This is actually a variation of my tuxedo cake, which originated from my chocolate cake recipe. In recent years, I’ve found that replacing sour cream for some of the buttermilk gives the cake more structure.
- Chocolate Mousse: I researched simplified ways to make a fluffy chocolate mousse filling without the use of eggs or gelatin. This chocolate mousse filling combines real chocolate and homemade whipped cream. Or our whipped frosting would make a wonderful alternative filling if you don’t want to make the chocolate mousse!
- Chocolate Ganache: Top the whole cake with 2 ingredient semi-sweet chocolate ganache. You should be a chocolate ganache pro by now!
Video Tutorial: Chocolate Mousse Cake
Stick-to-the-back-of-your-fork moist. This is every chocolate lover’s dream!
Dark Chocolate Cake
Use this chocolate cake as the starting point. For a sturdier, yet moister crumb, swap some sour cream in for the buttermilk and reduce the hot liquid. The acidity in both sour cream and buttermilk is a must to properly leaven this cake. (If desired, see baking powder vs baking soda for more information.) This cake has a natural dark chocolate taste, but to deepen that flavor, use a mix of natural cocoa and Hershey’s Special Dark cocoa powder. A touch of espresso powder and hot coffee further enhances the chocolate flavor. The cake will not taste like coffee. Rather, the two add depth to the cake’s chocolate flavor.
- Why hot liquid? The hot liquid encourages the cocoa powder to bloom and dissolve. If you don’t drink coffee, you can use hot water.
You have options! You can make this cake into 2, 3, or 4 layers. I highly recommend 3 or 4 layers because there’s over 4 cups of chocolate mousse to spread inside. You can use 8 inch or 9 inch pans. The bake times are similar, see recipe notes.
A cup of chocolate chips adds even more chocolate flavor. I used 1 cup (180g) of mini semi-sweet chocolate chips in this pictured cake, but left them out in the video. They’re optional, but definitely worth the addition!!
You can also see this exact cake batter baked as three layers in both my chocolate peanut butter cake and chocolate raspberry cake (try one of those next!).
Simplified Chocolate Mousse
The chocolate mousse adds a creamy and light contrast to the dark chocolate layers. You need 6 ingredients:
- Hot Water
- Cocoa Powder – natural or dutch-process
- Melted Chocolate – use two 4-ounce chocolate baking bars found in the baking aisle
- Heavy Cream
- Confectioners’ Sugar
- Vanilla Extract
Whisk the hot water and cocoa powder together. Pour into melted chocolate. The hot water breaks up the chocolate, adding to the airy mousse consistency. Cocoa powder creates additional chocolate flavor. Fold this chocolate mixture into whipped cream—a combination of heavy cream, confectioners’ sugar, and vanilla extract.
Whipped cream + our chocolate mixture. ↑
Fold them together to make our chocolate mousse filling. ↓
Baker’s Tip: The chocolate mousse must chill in the refrigerator before using, so it’s a good idea to make it ahead of time or as the chocolate cake layers are cooling. The mousse is best cold, so I actually recommend serving the cake cold. (Additionally, the cake is much easier to assemble if the mousse is cold!)
Chocolate Ganache
I won’t go into a lot of detail about the chocolate ganache because I have a complete chocolate ganache tutorial for you! Like the chocolate mousse, it’s imperative to use pure chocolate. Wait about 20 minutes for the ganache to thicken before pouring onto the cake.
How to Assemble & Decorate Chocolate Mousse Cake
Chocolate ganache enrobes 4 cake layers and 3 mousse layers. Place bottom cake layer on your cake stand or serving plate. Using a large icing spatula, evenly cover the top with about 1.5 cups of chilled chocolate mousse. Top with 2nd cake layer and another 1.5 cups of mousse. Top with the third cake layer, then spread another 1.5 cups mousse evenly on top. (Save a large spoonful of mousse for a thin crumb coat.) Top with final 4th cake layer. Spread any remaining mousse around the sides as a crumb coat. Run a bench scraper around the cake to smooth it out. Refrigerate cake for at least 1 hour and up to 4 hours. Chocolate mousse is pretty fluffy, so the cake won’t hold its shape unless it’s properly chilled.
Pour ganache on top then run a bench scraper around the sides to smooth it out. You can serve the cake immediately or wait for the chocolate ganache to set. 🙂
What About Cupcakes?
Instead of a big cake, you can make chocolate mousse cupcakes. Use my chocolate cupcakes recipe and halve the chocolate mousse and chocolate ganache recipes below. Fill the cupcakes with chocolate mousse using my Sugar Plum Fairy Cupcakes as an example. Drizzle cooled cupcakes with ganache. Eat your heart out!
You can also use the chocolate mousse instead of pastry cream in homemade mille-feuille!
More Indulgent Chocolate Desserts
- Dark Chocolate Bread Pudding
- German Chocolate Cake
- Flourless Chocolate Cake
- Black Forest Cake
- Chocolate Lava Cakes
- Chocolate Mousse Pie
- Mint Chocolate Cake
Dark Chocolate Mousse Cake
- Prep Time: 2 hours, 30 minutes (includes chilling)
- Cook Time: 25 minutes
- Total Time: 5 hours, 55 minutes (includes cooling)
- Yield: serves 12
- Category: Cake
- Method: Baking
- Cuisine: American
Description
This super moist dark chocolate cake combines unsweetened natural cocoa powder and dark cocoa powder for an extra rich flavor. Fill the cake with a simplified chocolate mousse and cover it with semi-sweet chocolate ganache. If needed, you can prepare the ganache and mousse ahead of time. See notes.
Ingredients
- 1 and 3/4 cups (219g) all-purpose flour (spooned & leveled)
- 3/4 cup (62g) unsweetened natural cocoa powder* (see note)
- 1 and 3/4 cups (350g) granulated sugar
- 2 teaspoons baking soda
- 1 teaspoon baking powder
- 1 teaspoon salt
- 2 teaspoons espresso powder (optional)*
- 1/2 cup (120ml) canola or vegetable oil
- 2 large eggs, at room temperature
- 3/4 cup (180g) full fat sour cream, at room temperature
- 1/2 cup (120ml) buttermilk, at room temperature*
- 2 teaspoons pure vanilla extract
- 1/2 cup (120ml) hot water or coffee*
- optional: 1 cup (180g) mini or regular semi-sweet chocolate chips
- optional garnish: fresh berries and/or chocolate shavings
Chocolate Mousse
- 1/2 cup (120ml) hot water
- 1/4 cup (22g) unsweetened cocoa powder* (see note)
- two 4-ounce quality semi-sweet chocolate bars (113g each), finely chopped*
- 2 cups (480ml) heavy cream or heavy whipping cream
- 2 Tablespoons (15g) confectioners’ sugar
- 1/2 teaspoon pure vanilla extract
Chocolate Ganache
- two 4-ounce quality semi-sweet chocolate bars (113g each), finely chopped*
- 1 cup (240ml) heavy cream or heavy whipping cream
Instructions
- Preheat oven to 350°F (177°C). Grease four 8-inch or 9-inch cake pans, line with parchment paper rounds, then grease the parchment paper. Parchment paper helps the cakes seamlessly release from the pans. (If it’s helpful, see this parchment paper rounds for cakes video & post.)
- Make the cake: Whisk the flour, cocoa powder, sugar, baking soda, baking powder, salt, and espresso powder (if using) together in a large bowl. Set aside. Using a handheld or stand mixer fitted with a whisk attachment (or you can use a whisk) mix the oil, eggs, and sour cream together on medium-high speed until combined. Add the buttermilk and vanilla and mix until combined. Pour the wet ingredients into the dry ingredients, add the hot water/coffee, and whisk or beat on low speed until the batter is completely combined. Fold in the chocolate chips, if using.
- Divide batter evenly between 4 pans. Bake for 19-23 minutes. Baking times vary, so keep an eye on yours. The cakes are done when a toothpick inserted in the center comes out clean.
- Remove the cakes from the oven and set on a wire rack. Allow to cool completely in the pan. The cakes may slightly sink in the middle as they cool—that’s expected.
- As the cakes cool, prepare the chocolate mousse so it can chill and be ready at the same time as the cake layers. You can also prepare the mousse 1-2 days ahead of time. Whisk the hot water and cocoa powder together. Set aside. Melt the chopped chocolate bars in a double boiler or use the microwave. If using the microwave: place the chopped chocolate in a medium heat-proof bowl. Melt in 20 second increments in the microwave, stirring after each increment until completely melted and smooth. Pour hot water/cocoa mixture into melted chocolate and stir until thick and smooth. Set aside. Using a hand mixer or a stand mixer fitted with a whisk attachment, whip the heavy cream, confectioners’ sugar, and vanilla extract together on medium-high speed until medium peaks form, about 3-4 minutes. Medium peaks are between soft/loose peaks and stiff peaks. Pour in the chocolate mixture and using a spoon or rubber spatula, gently fold together. Avoid over-mixing which can deflate/thin out the mousse. Cover mousse and chill in the refrigerator for at least 2 hours and up to 2 days. Makes about 4.5 cups chocolate mousse.
- Assemble layers before preparing chocolate ganache: First, level the cakes if needed: using a large serrated knife, slice a thin layer off the tops of the cakes to create a flat surface. Discard (or crumble over ice cream!). Place 1 cake layer on your cake stand, cake turntable, or serving plate. Using a large icing spatula, evenly cover the top with about 1.5 cups chocolate mousse. Top with 2nd layer and evenly cover the top with 1.5 cups chocolate mousse. Top with the third cake layer, then spread another 1.5 cups mousse evenly on top. Save a large spoonful of mousse for a thin crumb coat. Top with final 4th cake layer. Spread any remaining mousse around the sides as a crumb coat. Run a bench scraper around the cake to smooth out crumb coat. Refrigerate cake for at least 1 hour and up to 4 hours. Prepare the ganache as you wait.
- Chocolate Ganache: Place chopped chocolate in a medium heat-proof bowl. Heat the cream in a small saucepan over medium heat until it begins to gently simmer. (Do not let it come to a rapid boil– that’s too hot!) Pour over chocolate, then let it sit for 2-3 minutes to gently soften the chocolate. With a metal spoon or small rubber spatula, very slowly stir until chocolate has melted and mixture is smooth. The finer you chopped the chocolate, the quicker it will melt with the cream. If it’s not melting, do not microwave it. If needed, see Troubleshooting Chocolate Ganache. Once ganache mixture is smooth, let it cool for 20 minutes at room temperature before spreading on chilled cake.
- Pour/spoon ganache on chilled cake. Smooth the top with an icing spatula and the sides with a bench scraper. Top with optional garnish such as fresh berries and/or chocolate shavings. Serve cake immediately or chill, uncovered, for up to 4-6 hours before serving. Cake can be served at room temperature or chilled.
- Cover leftover cake tightly and store in the refrigerator for 5 days.
Notes
- Make Ahead & Freezing Instructions: Prepare cake through step 4. Wrap the individual baked and cooled cake layers tightly and refrigerate for up to 2 days or freeze up to 3 months. Bring to room temperature, make mousse filling, then continue with step 6. You can prepare the chocolate mousse in advance. See step 5. You can also prepare the chocolate ganache ahead of time too. Refrigerate prepared ganache for up to 2-3 days. Bring to room temperature before spreading onto cake. Frosted cake freezes well, up to 3 months. Thaw overnight in the refrigerator, then bring to room temperature or serve cold.
- Special Tools (affiliate links): 8-inch Round Cake Pans or 9-inch Round Cake Pans | Glass Mixing Bowl | Whisk | Electric Mixer (Handheld or Stand) | Cooling Rack | Double Boiler | Cake Stand or Cake Turntable | Large Icing Spatula | Bench Scraper | Cake Carrier (for storage)
- 3 Layer Cake: You can also prepare this cake as a 3 layer cake. Divide batter between three 8-inch or 9-inch cake pans in step 1 and bake for 22-25 minutes or until a toothpick inserted in the center comes out clean. Use about 2 cups of chocolate mousse between each layer.
- Espresso Powder/Coffee: Espresso powder and coffee will not make the cake taste like coffee. Rather, they deepen the chocolate flavor. I highly recommend them both. If coffee isn’t your thing, you can leave out the espresso powder and use extra hot water instead of the hot coffee.
- Cocoa Powder: For the best dark chocolate flavor in the cake, I recommend using a blend of unsweetened natural cocoa powder (1/4 cup; 22g) and Hershey’s “Special Dark” cocoa powder (1/2 cup; 43g). Hershey’s Special Dark is actually a mix of natural cocoa powder (an acid) and dutch-process cocoa powder (a base) and it worked fine in this recipe. This recipe needs acidic natural cocoa powder, so do not use ALL dutch-process cocoa powder. For best results, use 3/4 cup (65g) natural or the blend of natural/Special Dark I used. For the chocolate mousse, you can use either unsweetened natural or dutch-process cocoa powder. (Or the Hershey’s Special Dark.)
- Why Room Temperature? All refrigerated items should be at room temperature so the batter mixes together easily and evenly. Read more about why room temperature ingredients are important. Instead of sour cream, you can use plain yogurt. The cake won’t taste as rich, but it’s a fine substitute.
- Buttermilk: Buttermilk is required for this recipe. You can make your own DIY version of buttermilk if needed. Add 1 teaspoon of white vinegar or lemon juice to a liquid measuring cup. Then add enough whole milk to the same measuring cup until it reaches 1/2 cup. (In a pinch, lower fat or nondairy milks work for this soured milk, but the cake won’t taste as moist or rich.) Stir it around and let sit for 5 minutes. The homemade “buttermilk” will be somewhat curdled and ready to use in the recipe.
- Chocolate in Mousse & Ganache: Mousse & ganache will only set if the correct chocolate is used. You can use high quality chocolate chips if needed (I prefer Ghirardelli semi-sweet chocolate chips), but I recommend using pure chocolate baking bars. You can find them right next to the chocolate chips in the baking aisle. They are sold in 4 ounce bars. I like Bakers or Ghirardelli brands.
Made this cake last week. Absolutely delish!!! Sent more than half with hubby for his work; they loved and one said “best chocolate cake ever”. Making another for Thanksgiving.
Make as written!!
Thank you so much for letting us know, Lynn!
It was excellent. I absolutely loved it! Making it again today!
I made this with great success a few months ago. Do you think it could be adjusted to make a Swiss roll-esque thing? I loved the flavours and textures so much!
Hi Courtney, we’re so glad you loved this cake! We’d recommend using the chocolate mousse here in our chocolate Swiss roll cake. That uses a chocolate ganache topping, too. Let us know if you try it!
Made this today for my daughter’s friend. She requested a chocolate cake for her sweet 16 birthday. It came out so amazing. Recipe followed exactly except for using milk chocolate for the ganache!
Can you use gluten free flour, such as King Arthur A Cup for a Cup? Will it change the texture of the cake? Thank you
Hi Rachel, we haven’t tested it ourselves, so we’re unsure of the exact results. You can certainly give it a try, knowing the results will be different. Let us know if you do!
Hi, just made this recipe. I’m at the mousse part. When adding the melted chocolate into the whipped cream mixture, my mousse is very liquid….nothing like yours.
Any idea why or what to do? Thank you, Marie
Hi Marie, we’re happy to help troubleshoot. Was the heavy cream whipped into medium peaks before you added the chocolate mixture? Be careful not to overmix the two as well, as it can deflate the mousse and make it thinner.
Hi Sally and team! I am making this recipe for daughter’s Sweet 16. She wants your white chocolate buttercream rather than the mouse. I’ll divide the batter between 3 heart shaped pans. Two questions, please. (1) Should doubling the buttercream frosting be sufficient for 3 layers plus heavy piping decorations? As I’m frosting a dark cake with white buttercream, I’m guessing I’ll need a heavier coat. (2) If I chill the cakes, apply a crumb coat, and chill again before frosting, should that suffice to keep the dark cake from showing through the white frosting? Thanks so much!
Hi Amy, 2x the white chocolate buttercream should be sufficient, but it will really depend on the exact size of your cake layers and how heavily you plan to decorate it. Yes, a crumb coat will be helpful for helping the frosting to go on in a smooth layer without any crumbs of chocolate cake coming through. Hope it’s a hit!
Hi Sally, your recipes are always my go to one and I love it. Would this recipe fit in 9*13 inch pan and how long should i bake it for?
Hi Aswini, can’t see why not! This batter bakes in about 40 minutes in a 9×13 inch cake pan. Same oven temperature.
I have made this cake 3 times in past 2 months and every time it has been a success. It’s such a faultless recipe that nothing can go wrong. Only change I made was to use mix of dark and milk chocolate bars as we love dark chocolate. If you are adding chocolate chips make sure to give a light stir once the batter is in the pan as in my first attempt I forgot to do it in one pan and all the choco chips got settled at the bottom of that pan making the cake bottom lil wet.
Thanks for the recipe.
One Question: how do you stay skinny baking stuff like this???
My son requested a chocolate ganache cake for his 31st birthday. I could not have told you what “ganache” was prior to doing my online & youtube deep dive. I settled on Sally’s recipe because, well, it was SALLY’S recipe.
I had a lot of fun making this cake, but be forewarned that it takes all day — especially if you can’t seem to get it together at the grocery & have to make 3 trips to secure all the ingredients.
My son & his mother/my wife LOVED this cake. This might seem really odd given how much chocolate is in the cake, but it didn’t hit my chocolate “sweet spot.” I think that’s about me & not about the cake.
My family LOVES this cake so much! I’ve made this cake a dozen times and it’s a huge hit. Thank you so much! Question, if I wanted to switch up the mousse and make a peanut butter mousse, like your Homemade Eclairs with Peanut Butter Mousse Filling recipe, how much should I increase the mousse recipe?
Hi Cher Ann! I’m so glad to read that you enjoy this cake recipe. And my apologies, somehow I missed this comment/question. I feel as though 1.5x the peanut butter mousse recipe should be enough. Doubling would be far too much.
I’ve made this recipe a few times and love it! I have two occasions where I need a small chocolate cake. Would this convert this to two 6in cakes (3 layers each)?
Hi Katie, This would be too much batter for two 6 inch cake pans. We recommend using this chocolate cupcakes recipe as the batter to make a 3 layer 6 inch cake. See our 6 inch cake recipes post as a guide. Halve the chocolate mousse and ganache from this recipe so there’s just enough. Hope this helps!
I meant 2 3-later 6 inch cakes. I think I would need about 8c of batter. Does this make that amount?
I see! This recipe yields about 6 cups of batter.
Love this.. just made it and it was wonderful
I made this cake for my son’s 20th birthday party. I followed the recipe perfectly. Man it was so delicious!! It was almost hard to believe that I made it from scratch!! Thank you!!
This looks delicious! I was wondering how many cups of cake batter this recipe makes.
Hi Nicole, This recipe yields about 6 cups of batter.
Can you taste the coffee?
This cake is outstanding. Just made for a family party and it was a hit. Instructions are clear, flavor is rich and delicious. Will be making this again.Thank you!
The cake itself is phenomenal! I admit I have not tried the chocolate mousse version, but the chocolate cake has become the base for pretty much all chocolate cakes that I make. I have used chocolate butter cream, chocolate ganach and even swisse meuringe buttercream with raspberry for icing this cake. As this is the sour cream version of the triple chocolate cake, I come back to this recipe regularly. Thanks a lot for a detailed and well tested recipe!
I use many of your recipes and techniques and am always pleased with the results.
I have a question – have you made a chocolate cake using both natural and dutched cocoa powders ( with baking soda and baking powder)?
Hi Scott, we have used a combination of natural and Dutch process cocoa in this cake recipe without issue. See recipe notes for details, and let us know if you give it a try!
Can I use this recipe to make a layer cake that I buttercream? I’m not doing tiers but I am doing quite a few layers
Hi Dani, you can use buttercream instead of the mousse for this layer cake. Hope you enjoy it!
I love rich dark chocolare cake, but have been intimatedated to make this type of cake even though i make cakes all the time. This recipe does disappoint. It’s fantastic and worth the effort to make. I’m not going to lie, it’s rather involved and time consuming, but it’s worth the time, especially since a cake like this would cost at least $100 and probably woukdnt be as fresh. The direction for this cake are awesome and very detailed. Just follow them step by step and your cake will look professional. My friends and family loved it. It’s 5 star restaurant quality. Everyone can’t wait for me to make another.
I made this for my 15th birthday, and it was AMAZING!!! 🙂 Thanks so much for the delicious recipe!
This is the BEST cake I’ve ever had! I am NO baker and this cake makes me seem like I’m a pro! It doesn’t last long and there are never any leftovers! I am obsessed with this cake!!
I made this cake for my mother-in-law’s 75th birthday and it was delicious. I used the instructions for making ahead since I needed to transport it and assemble it elsewhere. I always appreciate when those types of instructions are included. I used 3 8-inch cake pans and followed all other directions exactly. It was really delicious-moist and full of chocolate goodness. I will definitely make this one again.
I tried this recipe 3 times already and always been a crowd pleaser and the best chocolate they’ve ever had! I was just wondering if I can make this into cupcakes? What will be the temperature pls and for how long? Thanks
Hi Kat, absolutely. See “What About Cupcakes?” section in the post for more details. Enjoy!
Can I use gluten free flour? Will it work?
Hi Deanne, We wish we could help but we haven’t tested this recipe with GF flour alternatives and have very little experience with them. Generally gluten free flours (the cup for cup measurement ones) work nicely in cakes.
How would this recipe do for a two-tier cake? Could it hold the weight of the 6in tier? I’m tasked with the cake for an 85th birthday party coming and and the guest of honor emphatically requested chocolate cake! Debating between this recipe and the triple chocolate.
Hi Rachel, we don’t have a chocolate cake recipe sturdy enough to be the bottom of a tiered cake at this time. It could work as a top tier, though! You can reference our cake pan sizes and conversions guide to adjust this recipe. And our homemade wedding cake post will provide our recommendations for a sturdy bottom tier. Let us know what you decide to try!
I made this as a two tiered wedding cake (gluten free even) and it worked amazingly! To note though: the top tier had a cardboard cake plate underneath it and I doweled the bottom tier.
Love this and all the cake recipes from Sally’s—consistent crowd-pleasers! I was wondering if you could provide recommendations on how the raspberry cake filling would best be incorporated into the layers (ie would the mousse hold up as a first layer/dam? Or if the mousse is too light, could the raspberry filling be spread as a first layer prior to mousse…or would it soak into the cake?) thank you!!
Hi Sophie! We would follow our recipe for chocolate raspberry cake instead.
I’ve made this three times so far and a friend just requested it for a very special birthday! This cake is perfect made exactly as written. Thank you, Sally, for your excellent, detailed instructions and delicious, reliable recipes.
Hi! I loved this recipe so much! Can it be turned into cupcakes though? I’d love to make some for my preschool students 🙂
Hi Carmi, absolutely. See “What About Cupcakes?” section in the post for more details. Enjoy!
This recipe is excellent. A few tips I would add after having made it is put a tbsp of butter in the ganache as you mix it to make it smoother as well as an inverted sugar like corn syrup a tsp or a tsp and a half works well if you don’t that in hand honey works the same way. As always the recipes she publishes are top tier. Also don’t skip the instant coffee or espresso powder as it makes the sponge even better.
Hi! What could I use instead of heavy cream? I was thinking about meringue, but I’m not sure.
I would appreciate your advice, TY.
Hi Vanessa, heavy cream/heavy whipping cream is necessary in this recipe for the mousse and ganache to set properly. We don’t recommend any substitutions.
I watched “Emily in Paris” when Gabriel made a chocolate cake for Emily’s birthday. Have you made a cake like that in the show? Could your Dark Chocolate Mousse Cake recipe be the same as the one in the show?