Chocolate Mousse Cake is a chocolate lover’s dream come true! Simple chocolate box cake is dressed up deliciously with a thick layer of chocolate mousse and decadent ganache.

Best Chocolate Mousse Cake Recipe
Sometimes, the best cake recipes are the ones from the box that you dress up! Box cake recipes are great because they save you a little bit of time from whipping up a homemade cake, and when you make them just right, they can be just as delicious as the real deal.
The real star of the show here isn’t the cake, though, it’s the mousse. Homemade chocolate mousse is something that I could eat a whole bowl of by itself, but when it’s sandwiched between chocolate cake and thick ganache, it becomes true heaven!
Speaking of ganache, that’s another thing I could eat all on its own! I don’t think any part of this cake would be bad all alone if I’m being honest. However, true magic happens when you assemble the base layer of simple chocolate cake, fluffy chocolate mousse, and thick, decadent ganache.
Why You’ll Love this Decadent Chocolate Mousse Cake Recipe:
- Box mix recipe: As much as I love making cake from scratch, box cake mixes are also a treasure! They’re a great way to save time and still have a delicious final result.
- Mousse: The chocolate mousse in this recipe is easy to make with simple foolproof steps and impossible to resist.
- Picturesque: Layered cakes are always gorgeous, especially when those layers include fluffy mousse. You’ll love snapping pictures of your chocolate creation!


How to Make Chocolate Mousse Cake for Any Occasion
Be sure to see the recipe card below for full ingredients & instructions!
- Use the box instructions to bake the cake. Allow it to cool completely.
Next, make the mousse –
- Combine and bloom the gelatin and cold water.
- Place chopped chocolate in a bowl.
- Simmer the heavy cream.
- Whisk in the gelatin, then pour the mixture over the chocolate.
- Whisk until melted.
- Allow the mixture to cool.
- Beat cream and powdered sugar together until peaks form.
- Stir in 1/4 cup of the whipped cream into the melted chocolate.
- Fold in the remaining whipped cream.
- Spread the mousse over the cake.
- Cover with plastic wrap and refrigerate.
Here’s how to make the ganache –
- Place the chopped chocolate in a bowl.
- Bring heavy cream to a simmer.
- Pour warm cream over the chocolate and allow to sit.
- Whisk until smooth and shiny, then pour it over the mousse.
- Cover and chill.


You sure can! Use your favorite chocolate cake recipe, or try my personal favorite homemade Devil’s food cake recipe!
If you only have gelatin leaves on hand, you can use 2 leaves of gelatin in place of the 2 teaspoons of powdered gelatin.
If your mousse turns out a bit runny, it’s probably because the whipped cream was not stiff enough before you incorporated the chocolate and gelatin mixture. Avoid this issue by whipping the cream until stiff peaks form.
Berries, chocolate shavings, and so much more can be used to garnish this gorgeous cake! You could always pipe some extra mousse on top of the cake before serving, too.

Recipe Tips and Tricks
- Your mousse needs time overnight to sit before the ganache is poured on top. Do not try to rush this process!
- Devil’s food cake or just regular chocolate cake are both great box mixes to use for this recipe.
- Heavy cream can NOT be substituted with whole milk, or anything else for that matter. Don’t even try it!

Chocolate mousse cake is a fantasy in all things decadent, delicious, and chocolatey!
If you make this recipe be sure to leave us a comment or rating. Enjoy!

Chocolate Mousse Cake Recipe
Ingredients
For the Cake
- 7⅝ ounces Devil's food cake mix 216 grams, such as Betty Crocker (½ box)
- ⅝ cup water 142 grams
- ¼ cup vegetable oil 50 grams
- 1 large egg 50 grams
- 1 egg yolk 14 grams
For the Chocolate Mousse
- 2 teaspoons powdered plain gelatin 6 grams
- 2½ tablespoons cold water 35 grams
- 2¼ cups chocolate chips 383 grams
- 3 cups heavy cream 681 grams, divided
- ½ cup powdered sugar 57 grams
For the Ganache
- ⅔ cup heavy cream 151 gams
- 8 ounces chocolate chips
- Chocolate shavings optional, for garnish
- Fresh berries optional, for garnish
Equipment
- Kitchen Scale (optional)
- Stand Mixer (optional)
- Hand Mixer (optional)
Instructions
For the Cake
- Prepare ½ package of cake mix according to the instructions on the box. The above ingredient measurements are for ½ box of Betty Crocker Devil's Food Cake, so be sure to use halved measurements for the appropriate ingredients if you use a different brand of cake mix. If your cake mix calls for 3 eggs, use 1 egg and 1 egg yolk as your halved measurement. Bake in a 9-inch springform pan according to the instructions (around 25 minutes) and let cool on a wire rack while you prepare the mousse.
For the Chocolate Mousse
- In a small bowl, combine the gelatin and cold water and bloom for 5-10 minutes.
- Meanwhile, place chocolate chips in a heatproof bowl. In a small saucepan set over medium-high heat, bring 1 cup of heavy cream to a simmer (between 112-115°F), then remove from the heat.
- Whisk in the bloomed gelatin and stir until completely dissolved. Pour mixture over the chocolate chips and whisk until melted and combined. Allow mixture to cool, stirring occasionally.
- In the bowl of a stand mixer fitted with the whisk attachment, or with a hand mixer in a large bowl, beat the remaining 2 cups of cream with the powdered sugar until stiff peaks form.
- Stir about ¼ cup of the whipped cream into the melted chocolate. Gently fold in the remaining whipped cream until fully incorporated.
- Spread the chocolate mousse evenly on top of the cooled cake while still inside the pan.
- Cover with plastic wrap and refrigerate for at least 8 hours or up to overnight.
For the Ganache
- Once the cake has chilled overnight, place the chocolate chips in a heatproof bowl. In a small saucepan set over medium-high heat, bring 1 cup of heavy cream to a simmer (between 112-115°F), then remove from the heat.
- Pour the warm cream over chocolate chips and allow to sit for 3-4 minutes, then whisk gently until smooth and shiny. Allow to cool until slightly thickened, then pour over the mousse.
- Cover and chill for 1 hour. Serve garnished with chocolate shavings and berries, if desired.
Notes
- Your mousse needs time overnight to sit before the ganache is poured on top. Do not try to rush this process!
- Devil’s food cake or just regular chocolate cake are both great box mixes to use for this recipe.
- Heavy cream can NOT be substituted with whole milk, or anything else for that matter. Don’t even try it!
- Nutritional information does not include optional ingredients.
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