A tall, thick layer of moist chocolate cake topped with a rich and creamy yet oh-so-light peanut butter mousse. This has quickly become a contender as one of my favorite cakes. It’s not overly sweet or heavy but still indulgent and delicious.
This cake was inspired by one from my favorite little eatery, Deru Market which is located in Kirkland, WA. The quality, freshness, and flavors of every item on their menu are unmatched. They sell their cakes by the slice and anytime I’ve gone, I cannot leave without a giant slice of their chocolate peanut butter cake. And then there’s the most amazing smoked turkey sandwich – with thin-sliced apple, sharp Beecher’s cheese, and homemade aioli all on scratch-made focaccia bread. I could eat that sandwich followed by a slice of the cake every single day and be perfectly content. I’m basically drooling now while I daydream about all their delicious food but back to that cake.
I’ve tasted cakes from many bakeries over the years and this chocolate peanut butter one from Deru takes the *cake* (wink, wink). I moved out of that area of Washington and now can’t quite justify the 4-hour drive it would take me to get there so I just had to recreate my own version. I’ve simplified it a bit from the original to create my chocolate peanut butter snack cake. Instead of a round layered cake coated with frosting, I turned this into a simple little snack cake. It’s one tall layer of chocolate cake, topped with a peanut butter mousse-like frosting that is light and airy.
Ingredients for Chocolate Peanut Butter Snack Cake
This is my go-to chocolate cake recipe. It’s simple, classic, and so moist. The peanut butter mousse is only 4 ingredients and comes together so quickly. It’s rich but just light enough. I could eat this stuff by the spoonful! Let’s go over what you’ll need for the cake and the mousse.
For the Chocolate Cake
- Cake Flour
- Baking Soda
- Baking Powder
For the Peanut Butter Mousse
- Peanut Butter
- Powdered Sugar
- Heavy Cream
How to Make Chocolate Peanut Butter Snack Cake
- Make the cake batter. The cake comes together using the classic creaming method. Cream the butter and sugar together until it’s light and fluffy then add eggs, vanilla, and cocoa powder. Then you’ll want to alternate between the dry ingredients and water. Be sure to scrap several times during the mixing process. This will ensure that all the ingredients are incorporated properly and will give you the best results once the cake is baked.
- Bake the cake. The cake gets baked in an 8” x 8” square cake pan or you can do a 9” x 9”, for a slightly shorter cake. I like to line the pan with parchment and leave the excess hanging over the sides to create a sling. This will make it so much easier to get the cake out of the pan and you won’t have to worry about it sticking to the bottom or the sides. When you bake the cake, you’re looking for the center of the to cake spring back to the touch and not sink back in.
- Make the mousse. Beat the peanut butter and butter together until it’s smooth and no lumps are left. I like to do this with a handheld mixer but it can be done with a stand mixer instead. Then mix in your powdered sugar. In another bowl, you’re going to whip the heavy cream until it reaches soft peaks and then mix that into the peanut butter mixture. You want to mix everything until it’s thick and smooth but be sure not to overmix it once the whipped cream is added.
- Frost the cake. I like to put a nice thick layer of the frosting on top and swirl it around in a random pattern. Sprinkle on some chopped peanut butter cups, chocolate sprinkles, or chocolate shavings to finish it off.
- Cut and enjoy. I like to cut this cake into 9 generous square pieces but you can cut them smaller if you want more of a bite-size piece. The mousse needs to be refrigerated so if you aren’t going to serve it immediately, be sure to stick the whole cake in the fridge. Just pull it out about 30 minutes before serving so the cake can warm up a bit. Then dive right into the chocolate peanut butter snack cake magic.
Tips for the Best Chocolate Peanut Butter Snack Cake
- Use a scale to measure your ingredients. I can’t ever stress this enough. Using weight to measure your ingredients is far more accurate than measuring cups. Kitchen scales are pretty inexpensive and this will also save you quite a few dishes. Who doesn’t love that?! I highly recommend using weight for all baking recipes and I include gram weights in my recipes.
- Scrape the bowl well. When making any cake batter, one of the most important parts is scraping the bowl often so that all the ingredients get incorporated. If you have a pocket of butter or flour that doesn’t get mixed in properly, it will show once the cake is baked. I generally scrape the bowl 5-6 times during the process.
- Keep the mousse refrigerated. The mousse needs to stay chilled because of the heavy cream in the icing. I like eating the cake when the chocolate cake is at room temperature and the mousse is chilled so I recommend making the mousse ahead of time and keeping it in the fridge until you’re ready to frost the cake. Give it a good mix so it’s spreadable, and then serve right away. This will give you the perfect bit of soft chocolate cake and chilled creamy frosting.
More Snack Cakes You’ll Love
This Chocolate Peanut Butter Snack Cake is simple, sweet, and scrumptious. It’s sure to be a new favorite. Happy Baking friends!
Chocolate Peanut Butter Snack Cake
For the Chocolate Cake
- ½ cup (113g) unsalted butter
- 1 ⅓ cup (285g) granulated sugar
- ½ cup (56g) cocoa powder
- 2 large eggs
- 1 teaspoon vanilla extract
- 1 ½ cups (160g) cake flour
- 1 teaspoon baking soda
- ½ teaspoon baking powder
- ¼ teaspoon salt
- 1 cup (204g) water
For the Peanut Butter Mousse
- ¾ cup (190g) creamy peanut butter
- ¼ cup (57g) unsalted butter
- ½ cup (60g) powdered sugar
- ¾ cup (6oz / 170g) heavy cream
For the Topping
- 8-10 Reese’s Miniature Cups, chopped (optional)
- Chocolate Cake: Preheat oven to 325°F. Lightly grease an 8” x 8” square pan with cooking spray. Line with parchment paper to create a sling, with an overhang on all four sides.
- In the bowl of a stand mixer fitted with a paddle attachment, cream the butter and sugar until fluffy and light in color, about 5 minutes.
- Add the eggs one at a time and vanilla, combining well after each addition. Scrape the bowl then add the cocoa powder. Start on the lowest speed and increase to medium speed until well combined. Scrape the bowl again.
- Sift together the cake flour, baking soda, baking powder, and salt. Alternate adding the flour mixture and water, starting and ending with the flour. Mix until just combined after each addition and scrape down the bowl a few times during the process.
- Pour batter into the prepared pan and smooth out the top. Bake for 45-50 minutes, or until the cake springs back to the touch (or a toothpick comes out clean).
- Allow the cake to cool completely before frosting.
- Peanut Butter Mousse: In a large mixing bowl, combine the peanut butter, and butter with an electric mixer until well combined and smooth with no lumps remaining. Add the powdered sugar and mix just until fully combined.
- In a separate bowl, whip the heavy cream to soft peaks then mix into the peanut butter mixture until thick and smooth.
- Spread the peanut butter mousse on the top of the cooled cake, using a tapered spatula and pushing the frosting just to the edges and corners.
- Sprinkle the chopped mini peanut butter cups on top, if desired. Slice the cake up and enjoy!
- Peanut Butter: I recommend using a thick, conventional peanut butter like Skippy or Jif. A natural variety won’t quite work the same in this recipe.
- Storing: Store the cake in an airtight container in the fridge for up to 3 days.