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chocolate mousse sheet cake

Chocolate Mousse Sheet Cake



For the "mousse" topping:

  • 1½ cups mini marshmallows
  • 1 cup semisweet or milk chocolate chips
  • ½ cup milk
  • 2 cups heavy cream
  • ¼ cup powdered sugar

For the cake:

  • 2 cups all-purpose flour
  • 2 cups granulated sugar
  • 1 teaspoon baking soda
  • ½ teaspoon salt
  • 2 eggs
  • ½ cup buttermilk
  • 1 teaspoon pure vanilla extract
  • 1 cup water
  • ½ cup unsalted butter
  • ¼ cup vegetable shortening
  • ¼ cup unsweetened cocoa powder
  • grated chocolate bar, for garnishing


  1. Before baking the cake, start the mousse topping. In a medium saucepan over medium-low heat, add marshmallows, chocolate chips and milk. Stir the mixture often until smooth and the marshmallows are melted. Once smooth, set aside and allow to cool completely.
  2. Set oven to 350 degrees F. Spray a 13×18 inch baking sheet with non-stick spray and set aside.
  3. In a mixing bowl fitted with the paddle attachment, add flour, sugar, baking soda and salt. Whisk well to combine. In a small saucepan over medium-high heat, add water, butter, shortening and cocoa powder. Stir occasionally, until the butter and shortening are melted and the mixture is smooth. Pour over the flour mixture and mix until combined. Add buttermilk and eggs and mix on medium speed until mixture is well combined.
  4. Pour batter into the prepared pan and spread evenly. Bake for 15-20 minutes, or until an inserted toothpick comes out clean. Allow cake to cool completely.
  5. To finish the mousse topping, clean out the mixing bowl and add heavy cream and powdered sugar. Mix on medium-high speed using the whisk attachment. Mix until cream is thickened and soft peaks form. Fold in cooled marshmallow chocolate mixture. Spread over the cooled cake and garnish with chocolate shavings.
  • Prep Time: 10 minutes
  • Cook Time: 20 minutes
  • Category: Dessert