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Chocolate Peanut Butter Cake

My favorite Chocolate Peanut Butter Cake filled with an easy peanut butter mouse and frosted with rich, chocolate fudge icing.


Units Scale
  • For cake:
  • 1 German Chocolate Cake mix (Duncan Hines is the one I used)
  • 3 heaping Tablespoons cocoa powder
  • 1 stick butter, melted
  • 3 large eggs
  • 1 1/4 cups milk
  • For Peanut Butter Mousse:
  • 2 cups peanut butter (not natural)
  • 8 ounces cream cheese
  • 1 cup powdered sugar
  • 1 teaspoon pure vanilla extract
  • 1 cup heavy cream, chilled
  • For Fudge Icing:
  • 1/2 cup butter
  • 4 heaping Tablespoons cocoa powder
  • 23 cups powdered sugar (may not need all of it)
  • 1/2 cup heavy cream
  • Pinch salt
  • For garnish:
  • Chopped peanut butter cups or chocolate shavings


  1. For cake: Preheat oven to suggested 350°F. Grease two 8- or 9-inch round cake pans; dust the inside with cocoa powder. Set aside.
  2. Place cake mix, cocoa powder, melted butter, eggs, and milk in a large mixing bowl. Beat with electric mixer on low speed for 30-60 seconds to combine the ingredients, then beat for -23 minutes on medium speed. Scrape down sides of bowl as needed.
  3. Divide batter between the cake pans. For two 8-inch cake pans, bake for 26–31 min; for two 9-inch pans, bake 23–28 min.
  4. Cool cakes for about 10 minutes in the pans. Run a thin knife around the edges to loosen and transfer the cakes to a wire rack to finish cooling. Refrigerate or freeze cakes, if desired, to make assembly easier.
  5. For Peanut Butter Mousse: In a medium mixing bowl, beat peanut butter and cream cheese with an electric mixer until creamy. Add the powdered sugar and vanilla. Beat until combined. The mixture will be thick.
  6. Clean the beaters and place chilled heavy heavy cream in a clean mixing bowl and beat until soft peaks form.
  7. Fold the whipped cream into the peanut butter in two additions. (The purpose of the first addition of cream is to lighten the mousse a bit so it doesn’t deflate.)
  8. Cover bowl and chill peanut butter mousse until ready to assemble the cake.
  9. For Fudge Icing: Place the butter in a medium saucepan. Melt over medium heat. Remove from heat and stir in cocoa powder.
  10. Using an electric mixer, beat in part of the powdered sugar and a few tablespoons of the heavy cream. Add more powdered sugar and cream until icing is at a spreadable consistency. Cover and set aside until ready to assemble cake. Can be made in advance and stored in refrigerator. Let come to room temperature and beat frosting again until spreadable.
  11. To assemble the cake: If desired, split the the two cake layers horizontally, or leave as-is. (For this cake, there were two 8″ rounds that I split into half horizontally to create 4 layers of cake and three layers of filling. The directions below reflect that.)
  12. Pipe or spread 1/4 of the PB mousse on the bottom layer. Top with next cake layer. Repeat with mousse and cake layers 2 more times.
  13. Spread top and sides with Fudge Icing. (There may be extra.)
  14. Pipe the remaining peanut butter mouse onto the top of the cake in a decorative pattern, if desired.
  15. Garnish the cake with chopped peanut butter cups and/or chocolate shavings, if desired. Enjoy it with a scoop of vanilla ice cream, or a huge glass of milk.


A homemade chocolate cake can be substituted for the cake mix, if desired.

  • Author: Lindsey Johnson
  • Category: Dessert
  • Cuisine: American