Chocolate Sheet Cake with Peanut Butter Frosting

Fudgy, beyond rich chocolate sheet cake topped with the creamiest peanut butter frosting. Feeds a crowd!

chocolate sheet cake topped with peanut butter frosting, drizzle of melted peanut butter, and peanut butter cups in a baking pan

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.

TGIF.

chocolate sheet cake topped with peanut butter frosting, drizzle of melted peanut butter, and peanut butter cups

I’m so excited because I’ve never shared a chocolate sheet cake recipe on my blog before.

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 in an office. And the entire thing disappeared in about .04 seconds. People flocked to it like it was a pot of shimmering gold under a rainbow.

pouring chocolate mixture into flour mixture in a glass bowl

2 images of thick chocolate cake batter in a glass bowl and whisked eggs and sugars in a glass bowl

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 favorite chocolate cake!). It’s completely incredible and truly deepens that chocolate flavor.

Then we’ll mix in all with dry ingredients. The usual suspects like flour, baking soda, and salt. Whisk eggs, sugars, and vanilla extract in another bowl. Combine all of these mentioned ingredients together, then whisk in some buttermilk.

chocolate cake batter in a glass bowl with a whisk

All of this chocolate magnificence goes into a half sheet pan.

Since it’s a thin cake, the bake time is quick. 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 enormous!

spreading peanut butter frosting onto chocolate sheet cake

↑ ↑ Best peanut butter frosting to ever grace this earth.

slice of chocolate sheet cake topped with peanut butter frosting, drizzle of melted peanut butter, and peanut butter cups on a white plate with a fork

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.

Print
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chocolate sheet cake topped with peanut butter frosting, drizzle of melted peanut butter, and peanut butter cups

Chocolate Sheet Cake with Creamy Peanut Butter Frosting

  • Author: Sally
  • Prep Time: 30 minutes
  • Cook Time: 20 minutes
  • Total Time: 2 hours, 50 minutes
  • Yield: serves 25-30
  • Category: Cake
  • Method: Baking
  • Cuisine: American

Description

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.


Ingredients

  • 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 eggs, at room temperature
  • 1 cup (200g) granulated sugar
  • 1/2 cup (100g) packed light brown sugar
  • 2 teaspoons pure vanilla extract
  • 1/2 cup (120ml) buttermilk, at room temperature*

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 milk*
  • 1 teaspoon pure 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 sprinkles*

Instructions

  1. Preheat oven to 350°F (177°C). Generously grease a 12×17 inch half sheet/jelly roll pan. Set aside.
  2. 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.
  3. 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.
  4. 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!
  5. 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.
  6. 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!

Notes

  1. Make Ahead & Freezing Instructions: 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.
  2. 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.
  3. Heavy Cream: Using heavy cream, half-and-half, or whole milk in the frosting produces the creamiest texture. (I use and highly recommend heavy cream.) If needed, you can use a lower fat or nondairy milk.
  4. 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.
  5. Toppings: 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)
  6. Sheet Pan: I own and love this 12×17 half sheet pan!
  7. Cake batter adapted from All Recipes.

Keywords: chocolate sheet cake, chocolate cake with peanut butter frosting

Add this to your weekend plans.

chocolate sheet cake topped with peanut butter frosting, drizzle of melted peanut butter, and peanut butter cups

149 Comments

  1. Hi Sally! Do you have a fan oven? If so is this temperature you are quoting for a fan oven or conventional oven? It would be really great if you could clear this up for me. I love your blog!!

    1. Conventional. All my recipes are written for conventional ovens, so adjust accordingly if you have a confection oven.

  2. Layla | Gimme Delicious says:

    Chocolate and peanut butter are a perfect combo. My daughter is obsessed with chocolate so I can’t wait to try this for her! 

  3. That looks amazing! I’m currently baking the “sugared lemon bars” from your book! Craving lemon:) can’t wait to taste them!!

  4. Made it tonight. Phenomenal!

  5. Abby (@ No Fail Recipes) says:

    Oh my! This cake looks so good. Peanut Butter and chocolate is my absolute favorite combination and I can’t wait to try this one. I would never have thought to substitute coffee for the water in the first step but I am definitely going to try that. Can’t wait to see how it turns out!

  6. Elaine @ FoodParsed says:

    Ohmigoodness, that is a lot of cake. The peanut butter frosting looks amazing, and it’s applied so nicely! I live in a college dorm, and this cake would make everybody very happy. 😀

  7. Cara @ The Little Blonde Baker says:

    Chocolate and Peanut Butter are the perfect combo! This cake looks PERFECT!

  8. Yum! Will definitely be trying this – sounds amazing!! Love the combination of pb and chocolate – hard to beat….

  9. MusingsonDinner (Chloe) says:

    Pure indulgence! I have a friend who loves – LOVES – chocolate and peanut butter. I’m going to share this with her

  10. Mmmm…sometimes you just need a good sheet cake in the kitchen. It’s the simple things in life!

  11. Hi Sally, What is your opinion on Hershey’s special dark cocoa powder which is a combo of natural and dutch process?    Can I use it in this recipe? (I already have it in my pantry).

    1. You can definitely use it in this recipe, yes. I love it!

  12. Kayle (The Cooking Actress) says:

    *swoon* sooo chocolatey sooo peanut buttery! This is the ultimate sheet cake, in my opinion!

  13. Hello my name is Kymra and I’m a Sally’s Baking Addiction addict :). I made these as cupcakes last weekend. They came out great! I baked them for 17 minutes and they were nice and moist. Delicious!

    1. Thanks for sharing that about the cupcakes! Happy you loved them.

  14. How about your peanut butter carmel corn on top!!  Love all you make! you’ve brought So many smiles and second helpings to my family’s  table! Thank you..;) 

  15. I just made this cake and the texture is incredible! The frosting tastes just like your peanut butter fudge, which is definitely the best fudge I’ve ever tried!

  16. Ariane Smith says:

    Hi Sally! I have always been a fan o‎f your recipes. I’ve made a few of them and my family are big fans of such delicious treats! I’m browsing on your cake recipes for our son’s First Communion next month and found this one, I think he would loooove this (PB and chocolate are his favorite thing in the world! Lol) btw, I’m wondering how to make the melted peanut butter for topping? I’ve never done that before and I don’t want to mess anything for the cake.. thank you! 🙂 

    Always your fan,
    Ariane‎

    1. It’s so simple! Use commercial style peanut butter like Jif or Skippy and melt in the microwave for 30ish seconds. Then drizzle on top. Hope everyone loves it!

      1. ariane smith says:

        thanks for the reply! have a great week!

  17. I want to make this, but I have kids. Since I gave kids they will eat it and one has a Milk allergy. Is there any way to use coconut milk?

    1. You can use coconut milk. See the recipe note to add a little lemon juice or white vinegar.

  18. Hey Sally!
    I really want to make this cake but my oven is kind of small and i don’t think a sheet pan that’s 12×17 will fit, if i were to make this in a nine inch round tin would that work? and also roughly how long would that take? Another option would be a 9×13 inch rectangle pan. Anyways thanks for taking the time to read this, absolutely love your recipes and would be happy to be able to try this one out! thanks 😀

    1. Candice, a 9×13 would be best but the cake will be thicker. I’m unsure of the exact bake time, but it will be much longer because the cake is so thick.

  19. That vanilla pudding version is genius!!

  20. Hi Sally, I just made the PB frosting for some brownies & it is delicious, however it made a lot…can the leftover frosting be frozen for later use?

    1. You can freeze the frosting. Let it thaw overnight in the refrigerator then bring to room temperature before using again.

  21. I made this cake for a bridal shower and everyone raved over it. Even the servers and cooks wanted some, which they could because there was plenty! I was nervous making a cake for a big event, but your recipes ALWAYS come out perfectly, so I was confident. Thank you so much for another wonderful recipe. 

  22. Hi, Sally!  My son has a peanut allergy – any of your icings that you would recommend to use instead that would generate enough icing to cover this gorgeous sheet cake?

    1. This fudge frosting. There will be plenty to use for this cake. Double chocolate! 🙂

  23. This is the first chocolate sheet cake I have ever made and will be the only recipe I’ll ever need! If you’re looking for a super fudgey chocolate cake that everyone will love then there’s no point in searching for any other recipe – this is the one, I promise!!

    1. Appreciate the comment, Karen, thanks!

  24. Could I make this in a bundt pan? 

    1. I can’t see why not!

      1. I made it 2 days ago and I’m currently making it again! Everyone loved it, it’s so fudgy and delicious! Thank you once again Sally for an amazing recipe. 

        P.s: I used the bundt pan and it took 30~35 minutes. 

  25. Can i add marshmellow fluff to the frosting?

  26. Could I use regular brown sugar instead of the light brown? 

  27. I am planning to make this for my daughter-in-laws birthday. Theses are her favorite flavors- I don’t usually have heavy cream on hand or full fat milk-can you use can milk?

  28. Hi Sally!
    I’m baking a chocolate cake for my boyfriends birthday and he loves the chocolate peanut butter combo. I wanted to do a layer cake though, would you suggest using your chocolate layer cake recipe and doing this peanut butter frosting or can you make this cake into a layer one? 

    Thanks!

    1. Hi Megan! I would just use the layer cake recipe.

  29. Made this over the weekend for a birthday celebration. It was a huge hit. Thank you, Sally!

  30. Hi Sally! So I want to make this cake as a graduation cake, but the person I am baking for requested their cake be half vanilla, half chocolate. Do you have any suggestions on how I could do that? I thought if I cut this recipe in half, and then your vanilla sheet cake recipe in half, and put them on either side of the sheet pan to bake that might work, but they may run together. The other idea I had was to bake each separately on half sheet pans and then put them together in a sheet pan to frost….what would you suggest? I hope you can help, thanks!

    1. What a great question and you definitely have the right idea! Here’s what I would do– two separate cakes (half sheet pans) then put together and frost. It would be difficult to get a clean line separating the two flavors.

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