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This Peanut Butter Chocolate Mousse Cake has a dense, chocolate cake bottom, followed by a peanut butter mousse layer, a chocolate mousse layer, and topped with chocolate ganache. It is rich, decadent, and all around amazing.
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4.93 from 13 votes

Peanut Butter Chocolate Mousse Cake

A dense chocolate cake bottom, topped with peanut butter mousse, followed by chocolate mousse, and finished with chocolate ganache. Rich, delicious, amazing.
Course: Dessert
Cuisine: Breakfast
Servings: 10 slices

Ingredients

Cake Layer

  • 1 ounce semi-sweet chocolate chopped
  • 1/4 cup cocoa powder
  • 1/3 cup strong hot coffee
  • 2/3 cup all purpose flour
  • 1/2 teaspoon salt
  • 1/2 teaspoon baking powder
  • 1/3 cup vegetable oil
  • 1/3 cup sugar
  • 1 teaspoons vanilla extract
  • 1/3 cup buttermilk
  • 1 egg

Peanut Butter Mousse Layer

  • 4 ounces cream cheese softened
  • 1/2 cup peanut butter
  • 1/3 cup powdered sugar
  • 1 teaspoon vanilla
  • pinch salt
  • 1/2 cup heavy cream

Chocolate Mousse Instructions

  • 4 large egg yolks
  • 1/2 cup sugar
  • 2 1/2 cups heavy cream divided
  • 3/4 cup semi-sweet chocolate chips
  • 1/4 cup dark chocolate chips

Chocolate Ganache

  • 1 cup dark chocolate chips
  • 1/2 tablespoon light corn syrup
  • 2/3 cup heavy cream

Instructions

Cake

  • Preheat oven to 350 degrees. Line 8" round pan with parchment paper, and butter/flour sides. I use Baking Pam for this.
  • In heat proof bowl, pour coffee over cocoa and chopped chocolate. Let sit for 2-3 minutes, then whisk together. Set aside.
  • In mixing bowl, whisk together flour, baking powder, and salt. Once mixed, add in chocolate/coffee mixture, oil, sugar, vanilla, buttermilk, and eggs. Beat until well combined.
  • Pour into prepared baking pan.
  • Bake for 18-20 minutes, or until toothpick in center comes out with just a few crumbs. Let cook in pan for 5 minutes, then remove to rack to finish cooling.

Peanut Butter Mousse

  • In large bowl using a handheld mixer, or in stand mixer, beat cream cheese, peanut butter, powdered sugar, vanilla and salt on medium-high for about 5 minutes, or until mixture is light and smooth.
  • Set bowl aside. In another bowl, using whisk attachment, beat heavy cream until peaks just begin to form, about 4 minutes. Fold cream into peanut butter mixture until well incorporated.
  • Next, put plastic over inside and sides of baking pan that you used for the cake. Then, fold a large piece of wax paper into thirds so that you have a long, thick piece (see photos). Place wax paper into pan so that it makes a tall side all around the pan.
  • Put the cake into the bottom of the pan. Spread peanut butter mousse evenly over the cake.
    peanut butter mousse
  • Put pan in freezer for at least 2 hours.

Chocolate Mousse

  • While peanut butter mousse is firming, start the chocolate mousse. IIn large bowl or stand mixer with whisk attachment, beat eggs for about 4 minutes, or until light colored and thickened. Then, beat in sugar.
    egg mix
  • Heat 1 cup of heavy cream in a medium sauce pot over medium heat. Once cream is hot, slowly pour a little over half of the cream into the egg yolk mixture, stirring continuously (it is important to do it slowly, and stir, so that you do not cook the eggs). Then, pour the mixture back into the remaining heavy cream in the pot, still stirring continuously.
  • Turn heat under pot to low, and stir continuously until mixture begins to thicken, about 5 minutes (if you use a very small pot, it may take closer to 10 minutes).
  • After mixture has thickened, remove from heat and whisk in chocolate chips until smooth.
  • Place mixture in bowl in fridge for at least two hours.
  • After mixture has chilled, beat remaining 1 1/2 cups whipping cream with whisk attachment until stiff peaks form, about 5 minutes.
    heavy cream
  • Fold whipped cream into chocolate/egg mixture until well combined.

Assembly

  • Remove cake with peanut butter mousse from freezer. Spread chocolate mousse evenly over peanut butter mousse and return to freezer for at least 2 hours.
    choc mousse layer
  • After chocolate mouse is firm in freezer, make ganache. To do this, place chocolate and corn syrup in heat proof bowl. In another bowl, heat heavy cream until bowling (I use a glass measuring cup in the microwave for about 30 seconds). Pour cream over chocolate/syrup and cover bowl with plastic wrap. Let sit for 5 minutes, then whisk until smooth.
  • Once smooth, spread about 3/4 cup of ganache over the chocolate mousse layer. Let the ganache cool and firm for at least 10 minutes, then gently remove the cake from the pan and peel off the wax paper. If the cake is sticking to the was, you can use a sharp knife to help remove it.
  • Allow the remaining ganache to cool to room temperature. At this point you can do several things: Place the ganache in a pastry bag and pipe decor,  beat the ganache with a mixer on high until lighter in color and fluffy (this will take about 5 minutes, and allows you to pipe the ganache similar to the way you would pipe buttercream), or allow it to fall down sides of cake. I also shaved chocolate to use on top as decor.

Notes

  • This can be made in a springform pan, but the cake will not be as tall. Also, you will need to bake the cake for a shorter length of time.
  • The chocolate mousse layer is minimally tweaked from a Betty Crocker recipe.