Easy chocolate mousse cake recipe makes a moist dark chocolate cake that’s topped with a simple, easy chocolate mousse. Easy homemade cake recipe that always gets rave reviews!
I like chocolate mousse anything – Chocolate Mousse, French Silk Brownies, and chocolate mousse brownies are just a few of the chocolate mousse treats that I love! So it isn’t surprising that this chocolate mousse cake is one of my favorite cake recipes!
This cake is moist and intensely chocolaty. It’s topped with a super rich and creamy chocolate mousse for the ultimate chocolate dessert.
And all of that chocolate in one little piece of cake means a super delicious dessert that’s perfect for birthdays, holidays, or any time you want something a little extra!
How to make chocolate mousse cake
In a medium bowl, whisk together flour, sugar, cocoa powder, baking soda, baking powder, and salt. Set aside.
In a large bowl, whisk together buttermilk and vegetable oil. Whisk in eggs one at a time.
Stir in dry ingredients until just combined.
Add hot water and vanilla. Whisk until just combined.
Pour batter into prepared baking dish.
Bake until wooden toothpick inserted in the center comes out clean. Cool to room temperature.
To make the chocolate mousse, add mini marshmallows, chocolate, and milk to a large, heavy saucepan.
Cook over low heat, stirring constantly, until melted and well-combined. Remove from heat, and cool completely.
In a large bowl, beat whipping cream and vanilla together to soft peak stage. Fold whipped cream into cooled chocolate mixture.
Spread over cooled cake. Chill for at least 30 minutes, or until ready to serve.
Tips
- Cocoa powder: I use regular unsweetened cocoa powder in this recipe. I’ve also used Hershey’s special dark cocoa powder. However, I haven’t tried Dutch-processed cocoa powder with this cake.
- Salt: If you don’t have kosher salt, use 1/2 teaspoon table salt instead.
- Buttermilk: Regular or low-fat will work. If you don’t have buttermilk, you can make a quick substitute with this recipe.
- Water: I use hot tap water about (150F).
- Semisweet baking chocolate: If you’d like a sweeter mousse, you can use milk baking chocolate.
- Milk: Any milk from skim to whole milk will work.
Tips for making whipped cream
If you haven’t made whipped cream (or would just like some tips), I have lots of tips and more pictures here.
Storage
The cake can be stored, covered, in the fridge for up to 5 days.
More chocolate cake recipes!
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Chocolate Mousse Cake
Equipment
- 9x13-inch metal baking pan
Ingredients
Chocolate Cake
- 1 ¾ cups all-purpose flour
- 1 ¾ cups granulated sugar
- 3/4 cups unsweetened cocoa powder
- 2 teaspoons baking soda
- 1 teaspoon baking powder
- 1 teaspoon kosher salt
- 1 cup buttermilk
- 1/2 cup vegetable oil
- 2 large eggs
- 2 teaspoons vanilla extract
- 1 cup hot water not boiling
Chocolate Mousse
- 1 ½ cups mini marshmallows
- 8 ounces semisweet baking chocolate chopped
- 1/2 cup milk
- 2 cups cold heavy whipping cream
- 1/2 teaspoon vanilla extract
Instructions
Chocolate Cake
- Preheat oven to 350 F. Grease a 9x13-inch baking pan. Set aside.
- In a medium bowl, whisk together flour, sugar, cocoa powder, baking soda, baking powder, and salt. Set aside.
- In a large bowl, whisk together buttermilk and vegetable oil.
- Whisk in eggs one at a time.
- Stir in dry ingredients until just combined.
- Add hot water and vanilla.
- Whisk until just combined.
- Pour batter into prepared baking dish.
- Bake 30-40 minutes, or until wooden toothpick inserted in the center comes out clean.
- Cool to room temperature.
Chocolate Mousse
- To make the chocolate mousse, add mini marshmallows, chocolate, and milk to a large, heavy saucepan.
- Cook over low heat, stirring constantly, until melted and well-combined.
- Remove from heat, and cool completely.
- In a large bowl, beat whipping cream and vanilla together to soft peak stage.
- Fold whipped cream into cooled chocolate mixture.
- Spread over cooled cake.
- Chill for at least 30 minutes, or until ready to serve.
- Refrigerate any leftovers.
Video
Notes
- Cocoa powder: I use regular unsweetened cocoa powder in this recipe. I've also used Hershey's special dark cocoa powder. However, I haven't tried Dutch-processed cocoa powder with this cake.
- Salt: If you don't have kosher salt, use 1/2 teaspoon table salt instead.
- Buttermilk: Regular or low-fat will work. If you don't have buttermilk, you can make a quick substitute with this recipe.
- Water: I use hot tap water about (150F).
- Semisweet baking chocolate: If you'd like a sweeter mousse, you can use milk baking chocolate.
- Milk: Any milk from skim to whole milk will work.
- Nutrition facts are estimates.
Nutrition
Did You Make This Recipe?
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Originally published 10/14/16. Updated with additional photos and tips 2/5/21.
Cake portion adapted from Food Network.
Reader Interactions
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Comments & Reviews
Kiley B says
Can you taste the marshmallow in the mousse?
Kate says
No, the mousse doesn’t taste like marshmallows.
Kiley B says
Thank you for the response! Making it for a friend who loves mousse but doesn’t like marshmallows so I wanted to check!
Susan Lostetter says
Am I able to make this into a layered cake with the mousse in between the layers? I’d like to make this for a birthday.
Kate says
I haven’t made it as a layer cake. The mousse is pretty soft, but it sets up well in the fridge. If you wanted to try making a layer cake, I would recommend frosting the first layer and then chilling it to let it set up before adding the second layer. I hope that helps!
Elii says
Hi there. Could I make the cake a week before and freeze it and put on the icing the day before my event?
Kate says
Hi! Yes, the cake freezes well, so that shouldn’t be a problem.
Kristi Locke says
This is absolutely delicious!! My house smells heavenly!!
Kate says
Thank you!
Barbara says
We made this cake for Father’s Day and it turned out so well! Everyone loved it. The mousse topping on the moist chocolate cake was a perfect combination. (Decided we could just make the mousse for a dessert sometime). This recipe was easy to make. A keeper!!
Kate says
Thank you!
Jessica says
The absolute best chocolate cake I’ve ever made. I used 2% because I didn’t have buttermilk. The mousse was incredible. I’ll definitely be make this over and over.
Kate says
Thank you!
Colette says
Can I make the mousse a day ahead of time? Or can I frost the cake the day before and refrigerate?
Kate says
The mousse is easier to use when it is freshly made, but you could frost the cake and refrigerate it.
Sandy says
Can I use gluten free flour
Kate says
Hi! I haven’t used that in this recipe, but I would guess that a measure-for-measure gf flour would work. If you give it a try, I’d love to hear how it turns out!
Aubrey says
Love love love!!! This has become a family staple at any get together!! I substituted the semi sweet for milk chocolate and oh my gosh! Game changer!!!!!
Kate says
Thank you!