Chocolate Sheet Cake with Creamy Peanut Butter Frosting
Fudgy, beyond rich chocolate sheet cake topped with the creamiest peanut butter frosting. Feeds a crowd!
Happiest of Fridays to you!
I saved a good one for today. I figured we can always use more peanut butter and chocolate on the weekend. Especially if that chocolate is rich beyond belief, that peanut butter is in the form of frosting, and that cake is the size of Texas.
And, of course, all those jazzy toppings.
I’m so excited because I’ve never shared a chocolate sheet cake recipe on my blog before. But there IS a funfetti version on my blog, naturally.
I’ve made this chocolate sheet cake a handful of times for various parties and I remember making it for an office party back when I worked full time. And the entire thing disappeared in about .04 seconds. People flocked to it like it was a pot of shimmering gold under a rainbow or something (can we blame them?). Oh my gosh, that was 3 years ago! I’ve been calling myself a full time blogger and confusing people with my job title who continue to ask “so it’s just for fun, right? what is your real job?” for 3 whole years. Where does the time go!?!
Let’s get right into this chocolate cake business. I posted this cake recipe over on Delish.com, but had to share it here as well. This chocolate sheet cake is actually a recipe I adapted from All Recipes back in the day. I sort of made it my own by changing up the method and adding more ingredients, using all butter and no shortening, reducing the sugar, using brown sugar where I could (surprised?), more cocoa powder, and completely switching up the frosting. It’s safe to say that this is one of the best chocolate cakes I’ve ever had, tasting almost identical to my popular chocolate layer cake recipe.
Have you tried that one yet?!
Some cake things you’ll need to know:
The first step we’ll do is melt down some butter with water and cocoa powder on the stovetop. This helps dissolve and hydrate the cocoa powder, which typically tends to dry cakes out. This also helps bring out the cocoa’s flavor. When mixed with a cup of butter, we have some seriously delicious chocolate liquid. Instead of water, you can use black coffee (like my triple chocolate layer cake!). It’s completely incredible and truly deepens that chocolate flavor.
Then we’ll mix it all with dry ingredients. The usual suspects like flour, baking soda, and salt. Baking soda because we’re using highly acidic natural unsweetened cocoa powder and buttermilk in this recipe. Remember what I taught you? In another bowl we’ll get those eggs, sugars, and vanilla extract whisked together. Combine all of these mentioned ingredients together, then whisk in some buttermilk. I highly advise against using any other milk besides buttermilk. The thickness, the acid, the taste brings so much to this cake! If anything, you can sour whole milk with a little vinegar or lemon juice to make a DIY buttermilk. See my recipe notes for more info.
Check out this chocolate batter. Taste testing is a dream.
All of this chocolate magnificence goes into a half sheet pan, the one I told you to buy the other day. Not only used for sheet cakes though! I use these as my cookie sheets and whatever I bake on a baking sheet in the oven like roasting vegetables, baked potatoes, baking fish, chicken wings, french fries, you name it!
Since it’s a thin cake, it won’t take long at all in the oven. Which means it won’t take long to cool, either. Which obviously means that you can cut into this chocolate cake and fall immensely in love sooner. But before all that, let’s frost it with the most unbelievable peanut butter frosting on the planet. It’s my go-to peanut butter frosting recipe, just made larger because this cake is ginormous and requires 25 gallons of frosting. An intense amount of peanut butter goes into the peanut butter frosting– much more peanut butter than butter. Why? For F-L-A-V-O-R. Make sure you use a commercial brand peanut butter, none of those natural kinds. There’s a lot of separating and texture issues if you use an oily, natural peanut butter in this frosting. I like Jif or Skippy.
↑ ↑ Best peanut butter frosting to ever grace this earth.
One bite = super moist, fudgy, tender, and decadent with a party of texture on top in the form of: peanut butter cups, melted peanut butter, chocolate sprinkles, peanut butter chips, and more. So I went a little overboard on the toppings but can you blame me? In the world of chocolate peanut butter cakes, we go big or we go home!
Chocolate Sheet Cake with Creamy Peanut Butter Frosting
Fudgy, beyond rich chocolate sheet cake topped with the creamiest peanut butter frosting. Feeds a crowd! I encourage you to read the full recipe and the recipe notes before beginning so you're completely prepared.
- 1 cup (230g) unsalted butter
- 1 cup (240ml) water
- 1/2 cup (42g) unsweetened natural cocoa powder (not dutch-process)
- 2 cups (250g) all-purpose flour (spoon & leveled)
- 1 teaspoon baking soda
- 1/4 teaspoon salt
- 2 large Eggland's Best eggs, at room temperature
- 1 cup (200g) granulated sugar
- 1/2 cup (100g) packed light brown sugar
- 2 teaspoons vanilla extract
- 1/2 cup (120ml) buttermilk, at room temperature1
Peanut Butter Frosting
- 1 and 1/2 cups (405g) creamy peanut butter (do not use natural style)
- 1/2 cup (115g) unsalted butter, softened to room temperature
- 3 cups (360g) confectioners' sugar
- 1/2 cup (120ml) heavy cream, half-and-half, or whole milk2
- 1 teaspoon vanilla extract
- pinch salt
- toppings: ½ cup (135g) melted creamy peanut butter for drizzling, 1 cup chopped peanut butter cups, handful of mini chocolate chips or peanut butter chips, and/or chocolate sprinkles3
- 12x17 half sheet pan (I own and love this one)
- Preheat oven to 350°F (177°C). Generously grease a 12x17 inch half sheet/jelly roll pan. Set aside.
- Heat the butter, water, and cocoa powder together in a large saucepan over medium heat. Whisk constantly until the butter has melted and everything is smooth and combined. Set aside. In a large bowl, whisk the flour, baking soda, and salt together. Pour the warm chocolate/butter mixture on top, then slowly whisk together until combined. It will be very thick.
- Whisk the eggs, granulated sugar, and brown sugar together in a medium bowl. The mixture will be thick. Whisk in the vanilla until combined, then pour into the chocolate batter and whisk until combined. Finally, whisk in the buttermilk. Pour the chocolate batter into the sheet pan.
- Bake for 15-20 minutes. (Mine takes exactly 17 minutes.) Use a toothpick to test for doneness: stick it into the cake. If the toothpick comes out clean, the cake is done. If not, continue baking. Remove cake from the oven and set the pan on a wire rack. Allow the cake to cool completely in the pan before frosting. The refrigerator helps speed things up, if you have room for the large pan!
- Make the frosting: Using a handheld or stand mixer fitted with a whisk attachment, beat softened butter and peanut butter together on medium-high speed for 2 minutes until completely smooth and creamy. Add the confectioners' sugar, cream, vanilla extract, and salt. Beat on low speed for about 20 seconds, then gradually increase to high speed. Beat on high for 1 minute until combined and frosting is fluffy. Taste; add more salt if needed. To thicken, add more confectioners' sugar and to thin, add more cream.
- Spread frosting all over cooled cake, then top with toppings. Slice and serve. Cover leftovers tightly and store in the refrigerator for up to 5 days. It's so good cold!
- Make ahead tip: Cake can be made 1 day in advance, covered tightly at room temperature, and then frosted before serving. Frosting can also be made 1 day ahead of time-- cover tightly and keep in the refrigerator. Bring frosting to room temperature before spreading. Frosted cake can be frozen up to 2 months; thaw overnight in the refrigerator and bring to room temperature before serving.
Room temperature ingredients: Here is why the ingredients must be at room temperature. The butter is melted and warm, so it's best the other ingredients are not cold. 🙂
- Buttermilk is a must for this recipe. You can sour milk to make a DIY version of buttermilk by measuring 2 teaspoons of lemon juice or white vinegar in a measuring glass. Add enough milk (whole milk is best) in the same measuring glass to reach 1/2 cup. Stir it around and let sit for 5 minutes. The soured milk will be somewhat curdled and ready to use in the recipe.
- A very thick cream or milk produces the BEST possible frosting. Heavy cream, half-and-half, or whole milk all work. For best taste and texture, do not use anything lower fat.
- So many toppings! Use what you like best. I also topped the cake with these Reese's peanut butter sprinkle ice cream topping (I found it near ice cream aisle)
Cake batter adapted from All Recipes
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