Go Back

Hot Chocolate Marshmallow Mousse Cake

Two desserts in one! Rich and moist chocolate cake topped with light and airy milk chocolate marshmallow mousse.
Prep Time 20 minutes
Cook Time 35 minutes
Total Time 2 hours
Servings 9 slices
Print Recipe Pin Recipe

Ingredients
  

  • 1 cup all-purpose flour
  • ⅔ cup granulated sugar
  • ⅓ cup unsweetened natural cocoa powder
  • 1 teaspoon baking soda
  • ½ teaspoon baking powder
  • ¼ teaspoon salt
  • 1 egg
  • ½ cup buttermilk
  • ¼ cup vegetable oil
  • 1 teaspoon pure vanilla extract
  • ½ cup hot coffee, or hot water

For the mousse

  • ¾ cup mini-marshmallows
  • ½ cup milk chocolate chips
  • ¼ cup whole milk
  • 1 cup heavy cream
  • ¼ teaspoon pure vanilla extract

Instructions

  • Preheat oven to 350°F. Grease an 8-inch square cake pan and line it with parchment paper.
  • In the bowl of a stand mixer fitted with the paddle attachment, add the dry ingredients for the cake and stir to combine.
  • Add the eggs, buttermilk, vegetable oil, and vanilla. Mix on low until combined.
  • With the mixer on low speed, slowly stream in the hot coffee. Beat on medium speed until smooth, about 2 minutes.
  • Pour the batter into the prepared cake pan.
  • Bake for 25-30 minutes, until a toothpick inserted in the center comes out clean.
  • Cool in the pan for 15 minutes, then transfer to a wire rack to cool completely.

For the mousse

  • In a pot over low heat, melt together the mini-marshmallows, milk chocolate, and milk. Stir constantly, until melted and combined, about 5-7 minutes. Remove from the heat and cool completely.
  • With a handheld mixer or stand mixer, beat the heavy cream and vanilla until soft peaks form.
  • Fold the whipped cream into the cooled chocolate marshmallow mix.
  • Spread over the cooled cake. Chill for 30 minutes, or until ready to serve.

Notes

Storage: Store covered in the refrigerator for up to 3 days.
Buttermilk: To make buttermilk, stir 1 teaspoon apple cider vinegar into ½ cup whole milk (or unsweetened soy milk) and let sit for 5 minutes.
Make it full-sized: For a 9×13-inch sheet cake, double the ingredients for both the cake and the mousse. Bake the cake for 30-35 minutes, until a toothpick inserted in the center comes out clean.
No stand mixer? Combine the dry ingredients for the cake in a large bowl and whisk to combine. Add the eggs, buttermilk, oil, and vanilla. Beat together with a handheld mixer or whisk. While whisking, slowly stream in the hot coffee. Whisk until smooth and combined.