Introduction

This Chocolate Mousse Cake combines a rich, moist chocolate cake base with a smooth and airy chocolate mousse topping. It’s a delightful dessert perfect for any chocolate lover looking to impress with a homemade treat.

A rectangular chocolate cake on a black cooling rack sits on a white marbled surface. The cake has one thick dark brown base layer topped with a generous, textured layer of light brown chocolate frosting spread unevenly with swirls and peaks. Small dark chocolate shavings are sprinkled over the frosting, adding texture and contrast. Around the cake, there is a small white bowl filled with dark chocolate chips, some scattered on the surface. A knife with chocolate frosting residue rests nearby. photo taken with an iphone --ar 4:5 --v 7

Ingredients

1 ¾ cups all-purpose flour
1 ¾ cups granulated sugar
¾ cups unsweetened cocoa powder
2 teaspoons baking soda
1 teaspoon baking powder
1 teaspoon kosher salt
1 cup buttermilk
½ cup vegetable oil
2 large eggs
2 teaspoons vanilla extract
1 cup hot water (not boiling)
1 ½ cups mini marshmallows
8 ounces semisweet baking chocolate (chopped)
½ cup milk
2 cups cold heavy whipping cream
½ teaspoon vanilla extract

Instructions

Step 1: Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking pan. Set it aside.
Step 2: In a medium bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and kosher salt until well combined.
Step 3: In a large bowl, whisk the buttermilk and vegetable oil together. Add the eggs one at a time, whisking well after each addition.
Step 4: Gently stir in the dry ingredients until just combined. Then add the hot water and vanilla extract, whisking until the batter is smooth.
Step 5: Pour the batter into the prepared pan and bake for 30 to 40 minutes. Check doneness by inserting a wooden toothpick in the center; it should come out clean.
Step 6: Allow the cake to cool completely to room temperature before adding the mousse.
Step 7: For the chocolate mousse, combine the mini marshmallows, chopped chocolate, and milk in a large heavy saucepan. Cook over low heat, stirring constantly until melted and smooth.
Step 8: Remove the saucepan from heat and let the chocolate mixture cool completely.
Step 9: In a separate large bowl, beat the cold heavy whipping cream with the vanilla extract until soft peaks form.
Step 10: Gently fold the whipped cream into the cooled chocolate mixture until fully incorporated.
Step 11: Spread the chocolate mousse evenly over the cooled cake. Chill the cake in the refrigerator for at least 30 minutes before serving.

Tips & Variations

For a more intense chocolate flavor, use dark cocoa powder in the cake batter.
Substitute mini marshmallows with marshmallow fluff if you prefer a smoother mousse texture.
Add a pinch of instant espresso powder to the dry ingredients to enhance the chocolate taste without altering sweetness.
Top the mousse with fresh berries or chocolate shavings for added texture and flavor.

Storage

Store the cake covered in the refrigerator for up to 3 days. To enjoy, remove from refrigerator about 15 minutes before serving to soften the mousse slightly. Avoid freezing, as the texture of the mousse may change.

How to Serve

A close-up view of rich, moist chocolate brownies cut into square pieces resting on a cooling rack over a white marbled surface, each brownie showing two layers: a thick, dark brown base layer with a dense texture, topped by a thick, light brown whipped chocolate frosting layer with soft peaks and a slightly rough surface, sprinkled with thin chocolate shavings for added texture. photo taken with an iphone --ar 4:5 --v 7

Serve this delicious recipe with your favorite sides.

FAQs

Can I use regular milk instead of buttermilk?

Yes, you can substitute buttermilk with regular milk mixed with 1 tablespoon of lemon juice or vinegar per cup. Let it sit for 5 minutes before using to mimic buttermilk’s acidity.

Is it necessary to chill the cake before adding the mousse?

Chilling the cake ensures it has cooled completely, which prevents the mousse from melting or becoming too soft when spread on top. It helps maintain the mousse’s light texture.