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–+ servings
a slice of chocolate mousse cake on a white plate topped with a strawberry.

Triple Chocolate Mousse Cake Recipe

Course: Cake, Dessert
Cuisine: American
Prep Time: 25 minutes
Cook Time: 35 minutes
Chill: 9 hours
Total Time: 10 hours
Servings: 10 slices
Calories: 792kcal
Author: Becky Hardin
A rich triple chocolate mousse cake that looks fancy but is surprisingly simple. Start with boxed Devil’s food cake, top with stabilized chocolate mousse, and finish with a glossy ganache.
Print Recipe
US Customary - Metric

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
    chocolate cake batter in a springform pan.
  • 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.
    placing a baked chocolate cake on a cooling rack in a springform pan.

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
    blooming gelatin in water in a small glass bowl.
  • 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
    heating cream in a saucepan.
  • Whisk in the bloomed gelatin and stir until completely dissolved.
    adding bloomed gelatin to heavy cream in a saucepan.
  • Pour the mixture over the chocolate chips.
    pouring gelatin-infused heavy cream over chocolate chips.
  • Whisk until melted and combined. Allow the mixture to cool, stirring occasionally.
    chocolate gelatin mixture in a bowl.
  • 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
    beating cream and powdered sugar to stiff peaks with a hand mixer.
  • Stir about ¼ cup of the whipped cream into the melted chocolate. Gently fold in the remaining whipped cream until fully incorporated.
    whipped chocolate mousse mixture in a bowl.
  • Spread the chocolate mousse evenly on top of the cooled cake while still inside the pan.
    spreading chocolate mousse over chocolate cake in a springform pan.
  • Cover with plastic wrap and refrigerate for at least 8 hours or up to overnight.
    chocolate mousse cake covered with plastic wrap in a springform pan.

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
    heating heavy cream in a saucepan.
  • Pour the warm cream over the chocolate chips and allow to sit for 3-4 minutes.
    pouring heavy cream over chocolate chips.
  • Whisk until smooth and shiny.
    chocolate ganache in a glass bowl with a whisk.
  • Allow to cool until slightly thickened, then pour over the mousse.
    pouring chocolate ganache over chocolate mousse cake in a springform pan.
  • Cover and chill for 1 hour. Serve garnished with chocolate shavings and berries, if desired.
    Chocolate shavings, Fresh berries
    set chocolate mousse cake topped with a sliced strawberry.

Video

Notes

*I used Betty Crocker Devil's food cake, but any kind of chocolate cake will work. Or try my homemade Devil's food cake recipe!
**Use gelatin leaves instead of powder (2 leaves = 2 tsp).
Tips:
  • 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.
Make-Ahead: Bake the cake and chill the mousse overnight, then add the ganache the next day; the cake will keep in the fridge up to 3 days.
Storage: Store chocolate mousse cake in an airtight container in the refrigerator for up to 5 days or in the freezer for up to 2 months.

Nutrition

Serving: 1slice | Calories: 792kcal | Carbohydrates: 65g | Protein: 5g | Fat: 59g | Saturated Fat: 33g | Polyunsaturated Fat: 6g | Monounsaturated Fat: 11g | Trans Fat: 0.04g | Cholesterol: 136mg | Sodium: 212mg | Potassium: 344mg | Fiber: 1g | Sugar: 53g | Vitamin A: 1335IU | Vitamin C: 1mg | Calcium: 141mg | Iron: 1mg