This chocolate mousse cake is pure decadence in every bite. I top a moist Devil’s food cake with fluffy homemade chocolate mousse and finish it all off with a glossy chocolate ganache. It’s rich and indulgent, but surprisingly easy to make, especially since the cake starts with a boxed mix!
Layered Chocolate Mousse Cake with Chocolate Ganache
This layered chocolate mousse cake may look fancy, but it starts with a box of Devil’s food cake mix–so easy! The homemade mousse is light and airy, the ganache is glossy and silky, and the only real effort is waiting for each layer to set.
If you’ve ever had mousse turn grainy or separate, gelatin is my trick that keeps it smooth and sliceable. It helps this triple-layer cake hold its shape while still feeling light and melt-in-your-mouth creamy. I make this recipe for Valentine’s Day, dinner parties, and birthdays whenever I want a show-stopping chocolate dessert.
Email this Recipe
Enter your email and we’ll send the recipe directly to you!
By submitting this form, you consent to receive emails from Easy Dessert Recipes.
My Keys to Success
The key to a smooth, sliceable triple chocolate mousse cake is temperature control and gentle folding. Let the melted chocolate cool to room temperature before folding it into the whipped cream (so it doesn’t deflate it!), and stop whipping the cream once it reaches stiff peaks. Those two steps keep the mousse fluffy, stable, and perfectly creamy.
Triple Chocolate Mousse Cake Recipe
Equipment
- Kitchen Scale (optional)
- 9-inch Springform Pan
- Hand Mixer or Stand Mixer
Ingredients
For the Cake
- 7.625 ounces Devil’s food cake mix (½ of a 15.25-ounce box)*
- ⅝ cup water
- ¼ cup vegetable oil
- 1 large egg
- 1 large egg yolk
For the Chocolate Mousse
- 2 teaspoons powdered plain gelatin **
- 2½ tablespoons cold water
- 2¼ cups chocolate chips
- 3 cups heavy cream divided
- ½ cup powdered sugar
For the Ganache
- 8 ounces chocolate chips
- ⅔ cup heavy cream
- Chocolate shavings optional, for garnish
- Fresh berries optional, for garnish
Instructions
For the Cake
- Prepare ½ package of cake mix according to the instructions on the box with water, vegetable oil, and eggs.7.625 ounces Devil’s food cake mix, ⅝ cup water, ¼ cup vegetable oil, 1 large egg, 1 large egg yolk
- 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.2 teaspoons powdered plain gelatin, 2½ tablespoons cold water
- Meanwhile, 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.2¼ cups chocolate chips, 3 cups heavy cream
- Whisk in the bloomed gelatin and stir until completely dissolved.
- Pour the mixture over the chocolate chips.
- Whisk until melted and combined. Allow the 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.½ cup powdered sugar
- 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 ⅔ cup of heavy cream to a simmer (between 112-115°F), then remove from the heat.⅔ cup heavy cream, 8 ounces chocolate chips
- Pour the warm cream over the chocolate chips and allow to sit for 3-4 minutes.
- Whisk 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.Chocolate shavings, Fresh berries
Notes
- Let the cake cool completely before adding the mousse to prevent weeping.
- Let the chocolate mixture cool to room temp. before folding it into the whipped cream, and whip the cream to stiff peaks to avoid a runny mousse.
- Fold the chocolate and whipped cream together gently to keep the mousse light and airy.
- Chill the mousse for 8-9 hours or overnight before adding the ganache.
- Let the ganache cool until thick but pourable, and pour slowly to avoid sinking into the mousse.
- Chill the cake for 1 hour before slicing.
- Let the cake sit for 15 minutes at room temp. before serving for the best texture.
- For clean slices, dip a sharp knife in hot water and wipe between cuts.
- Nutritional information does not include optional ingredients.
How to Make Chocolate Mousse Cake Step-by-Step
Bake the Cake: Prepare 7.625 ounces (½ box) of chocolate cake mix using ⅝ cup of water, ¼ cup of vegetable oil, 1 large egg, and 1 large egg yolk. Pour the batter into a 9-inch springform pan and bake according to the box directions (about 25 minutes at 350°F). Once it’s done, cool it completely on a wire rack before you add anything else–if the cake is even a little warm, it can melt the mousse. If you want to use the full box, you can bake both layers, freeze one for later, or use the mousse as a filling for a double-layer cake.
Bloom the Gelatin: While the cake cools, bloom 2 teaspoons of powdered gelatin in 2½ tablespoons of cold water. Let it sit for 5-10 minutes so it absorbs the liquid and starts to thicken. Gelatin stabilizes the mousse so it stays sliceable, while whipped cream keeps it airy. Make sure it fully blooms; otherwise, your mousse may turn out grainy.
Melt the Chocolate: Meanwhile, place 2¼ cups of chocolate chips in a heatproof bowl. In a small saucepan, heat 1 cup of heavy cream until simmering (112–115°F), then stir in the bloomed gelatin until fully dissolved. Pour the hot cream/gelatin mixture over the chocolate chips, and whisk until smooth and melted. Let the chocolate cool to room temperature (about 15–20 minutes). If you add warm chocolate to cold cream, it can make the mousse grainy or separated, so don’t rush this step.
Whip the Cream: In a stand mixer or with a hand mixer, beat the remaining 2 cups of heavy cream with ½ cup of powdered sugar until stiff peaks form. If the cream isn’t whipped enough, your mousse will be runny. Stop whipping right when stiff peaks form, so it doesn’t turn grainy or start to separate.
Mix the Mousse: Stir about ¼ cup of the whipped cream into the chocolate mixture to lighten it. Then, gently fold in the remaining whipped cream until fully combined. Fold gently so you don’t knock out all the air–the lighter you keep it, the fluffier the mousse will be.
Chill the Mousse: Spread the mousse evenly over the cooled cake while it’s still in the pan. Cover with plastic wrap and refrigerate for at least 8 hours or overnight. The mousse needs time to set properly before you add the ganache. Don’t rush this step. If you made 2 layers of cake, wait until the mousse has set overnight to place the second layer on top.
Make the Ganache: Once the mousse is fully set, place 8 ounces of chocolate chips in a heatproof bowl. Heat ⅔ cup of heavy cream in a small saucepan until simmering (112–115°F), then pour it over the chocolate chips. Let everything sit for 3-4 minutes, then whisk until smooth and shiny. Let the ganache cool until it’s thick but still pourable, then pour it gently over the mousse. If the ganache is too warm, it can sink into the mousse, so let it cool a bit first.
Set the Ganache: Cover the cake and chill for 1 hour, then slice and serve. For clean slices, dip a sharp knife in hot water and wipe it between cuts. Let the cake sit 10-15 minutes at room temp. before serving for the best texture. Serve garnished with chocolate shavings and berries, if desired.
How to Store and Freeze
Store your three-layer chocolate mousse cake in an airtight container in the fridge for up to 5 days, or freeze individual slices wrapped tightly in plastic wrap and stored in a freezer-safe container for up to 2 months. Thaw in the fridge overnight before serving. I like to serve it slightly chilled.
Leave a Reply