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!
“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.” – Jessica
Ingredient notes and substitutions
- 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.
- Oil: Feel free to use another type of neutral oil like canola oil or olive oil.
- 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.
How to make chocolate mousse cake
Here you’ll find step-by-step photos showing how to make this recipe. The full recipe, including ingredients, is given below.
Step 1: In a medium bowl, whisk together flour, sugar, cocoa powder, baking soda, baking powder, and salt. Set aside.
Step 2: In a large bowl, whisk together buttermilk and vegetable oil. Whisk in eggs one at a time.
Step 3: Stir in dry ingredients until just combined.
Step 4: Add hot water and vanilla. Whisk until just combined.
Step 5: Pour batter into prepared baking dish.
Step 6: Bake until wooden toothpick inserted in the center comes out clean. Cool to room temperature.
Step 7: To make the chocolate mousse, add mini marshmallows, chocolate, and milk to a large, heavy saucepan.
Step 8: Cook over low heat, stirring constantly, until melted and well-combined. Remove from heat, and cool completely.
Step 9: In a large bowl, beat whipping cream and vanilla together to soft peak stage.
Step 10: Fold whipped cream into cooled chocolate mixture.
Step 11: Spread over cooled cake. Chill for at least 30 minutes, or until ready to serve.
Recipe Tips!
- Metric: You can the weights for the ingredients by clicking on “metric” immediately above the ingredients.
- Grated chocolate: I grate a little chocolate over the top of the cake for looks and a bit of texture.
Recipe FAQs
This recipe has had hundreds of comments and questions. Here are some answers to some of the most commonly asked questions.
You can! The cake freezes well. Once the baked cake has cooled to room temperature, wrap it tightly in plastic wrap and then wrap it in aluminum foil. The cake will keep for up to 1 month in the freezer.
No, you can’t taste the marshmallows in the mousse. They help to make it light and fluffy, but it tastes like chocolate, not marshmallows.
The cake keeps well in the fridge. You can make it up to 1 day before serving and store it in the refrigerator.
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 refrigerator. It will keep for up to 5 days when properly stored in the fridge.
More chocolate cake recipes!
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Chocolate Mousse Cake
Equipment
- 9×13-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 9×13-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. Post is updated regularly with new photos, tips, and information.
Cake portion adapted from Food Network.
Reader Interactions
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Comments & Reviews
Lori says
This is my 3rd time making this cake, it’s delicious! Everyone loves it. Thank you. Great dessert for Easter, God Bless
Kate says
Thank you! And Happy Easter to you!
Christianne Brooks says
The all around best chocolate cake ever. Today is my 2nd time making it and I am going to do cupcakes instead of 9/13 Thank you for sharing
Kate says
Thank you so much!
Negri says
This is an amazing moist and delicious cake. You can even eat the cake without the mousse, that’s how good this cake is. My question is, can I make it as cupcakes as opposed to a full size cake? And if so, will the baking degree and time will be the same or different?
Kate says
Thank you! I haven’t made this recipe as cupcakes, but I don’t see any reason that it wouldn’t work. For cupcakes, it should be 350F for about 18-22 minutes. The timing may vary depending on your oven. Hope that helps!
TS says
Excellent cake. The cake itself is super moist and probably the best chocolate cake I ever had. The icing pairs perfectly. It literally tastes like chocolate mousse. Will definitely keep this one!
Kate says
Thank you so much!
Cindy Petri says
Delightfully rich!
Kate says
Thank you!
Helene says
Easy to follow recipe that comes out perfect. The chocolate mousse frosting is delicious and is a wonderful alternative to buttercream frosting. My go to recipe for chocolate cake!
Kate says
Thank you so much!
Kirsten Aysu says
Made it for my pottery class and they loved it!
Kate says
Yay! I’m so glad that it was a hit!
denise says
HI, Im wondering if we can use semi sweet chocolate chips?
Kate says
Hi! Yes, you can use semisweet chocolate chips.