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Mousse Cake

Mousse Cake

The bottom layer of the mousse cake is a hazelnut mousse, with hazelnut brownie in the middle. Topped with a layer of white chocolate mousse and strawberries. With ganache on top, Lindt truffles, and strawberries.
Course Dessert
Cuisine American
Keyword cake, mousse
Prep Time 1 hour
Cook Time 30 minutes
Resting time 12 hours
Servings 12 people
Calories 550 kcal

Ingredients

Brownie

  • 1/4 cup unsalted butter room temperature (4 tablespoons, 2 ounces, 56 grams)
  • 2 tablespoons oil canola, avocado, or any vegetable oil
  • 1 cup granulated sugar 7 oz, 200 grams
  • 2 large eggs room temperature
  • 1/2 cup all-purpose flour 2.25 oz, 63 grams
  • 1/3 cup unsweetened cocoa powder
  • 1 teaspoon espresso powder
  • 1/2 teaspoon baking powder
  • 1/4 teaspoon fine sea salt
  • 1/2 cup chopped chocolate* Note 1

Hazelnut Mousse

  • 2 teaspoons powdered gelatin about 7 grams, 0.24 oz, 1 sachet
  • 3 tablespoons cold water
  • 1 1/3 cups heavy cream divided
  • 5 oz chopped chocolate or chocolate chips (about 3/4 cup, 141 grams)** (Note 2)
  • 1/3 cup hazelnut paste recipe for the easy paste below or you can sub nutella*** (Note 3)

White Chocolate Mousse

  • 4 teaspoons gelatin powder about 14 grams, 0.49 oz, 2 sachets
  • 6 tablespoons cold water
  • 10 oz chopped white chocolate about 1 1/2 cups, 283 grams
  • 2 tablespoons powdered sugar
  • 2 2/3 cup heavy cream divided

Chocolate Ganache

  • 4 ounces chocolate chopped, or chocolate chips (2/3 cup chocolate chips, 113 grams)
  • 1/2 cup heavy cream

Quick Chocolate Buttercream (optional to pipe on top of the cake)

  • tablespoons  unsalted butter 2 oz, 56 grams
  • 1/4  cup  cocoa powder
  • 2 1/2  cup  powdered sugar
  • 1/2  teaspoon  vanilla extract

To assemble

  • Strawberries
  • Chocolate Truffles

Instructions

Brownie

  1. Prepare a 8” baking pan and spray it with non-stick spray, and line the bottom and sides with parchment paper, or grease the pan with butter and flour. Set aside.
  2. Pre-heat oven to 350F.
  3. Mix butter and oil in the bowl of a stand mixer. Whisk briefly to combine. Add sugar and keep mixing until ingredients come together. Add eggs, one at a time, mixing one egg entirely before adding the next one.
  4. Sift flour, cocoa powder, espresso powder, baking powder, and salt together. Add to the mixture. Mix with a spatula to fold ingredients. Add chopped chocolate and nuts (if using - read note 1).
  5. Pour batter onto pan. Bake for 20-30 minutes. A toothpick should come out clean when inserted in the cake.
  6. Set it aside to cool completely. Store it in the refrigerator until it’s time to assemble the cake. You want the brownie to be cold for the assembly.

Hazelnut Mousse

  1. Add powdered gelatin to cold water. Mix to combine. Set it aside to let it bloom for 5-10 minutes.
  2. Place chocolate and hazelnut paste (or nutella, or any hazelnut spreain a heat proof bowl. Set aside.
  3. Add 1/3 cup of the heavy cream to a small saucepan. Bring to a slight boil over medium heat.
  4. As soon as you see it coming to a boil, turn the heat off.
  5. Add gelatin to the cold heavy cream. Whisk until the gelatin has melted entirely.
  6. Pour hot cream mixture over chocolate and hazelnut paste. Mix until the chocolate has melted completely. If necessary pop the bowl in the microwave for a few seconds, mixing in between, until the chocolate has melted.
  7. Set aside to cool slightly.
  8. Pour the remaining 1 cup of heavy cream in the bowl of an electric mixer. Whip on high until the cream has stiff peaks. It will take about 2 minutes.
  9. Add the cream in three parts to the mousse, and fold carefully with a spatula. Once combined, add the second part, fold. And then, add the rest of the whipped cream. Fold until the mixture is smooth.
    folding whipped cream in mousse

To assemble Hazelnut Mousse

  1. Place the brownie in the bottom of a 9” silicone round pan on top of a baking sheet, to provide a sturdy base for the silicone pan.

    brownie in silicone pan for mousse cake
  2. Pour mousse over brownie. Tap the baking sheet a few times against the counter to release air bubbles.

    hazelnut chocolate mousse
  3. Place it in the freezer for 6 hours, or overnight.

White Chocolate Mousse

  1. Mix gelatin powder with cold water. Let it sit so the gelatin will bloom. Meanwhile place the white chocolate in a heat proof bowl.
  2. Place 2/3 cup of heavy cream in a small sauce pan. Bring it to a boil over medium heat. Turn off the heat. Add gelatin mixture to the hot cream, whisk until melted. Pour hot cream and gelatin over white chocolate. Let mixture sit for 1 minute. Start stirring to combine. If the white chocolate doesn’t melt entirely after a while stirring, place it in the microwave for a few second intervals, stirring in between, until the chocolate is melted.
  3. Whip 2 cups of heavy cream with 2 tablespoons of powdered sugar in the bowl of an electric mixer. Whip on high for 1-2 minutes until stiff peaks form.
  4. In three parts, mix the whipped cream in the mousse. Add 1/3 of it to the white chocolate. Fold carefully until combined. Add another 1/3 of the mixture. Fold until combined. Add the remaining whipped cream. Fold until completely incorporated.

To assemble White Chocolate Mousse

  1. Thinly slice some strawberries and place them on the sides of the silicone pan.

    strawberry silicone pan white chocolate mousse
  2. Then pour the mousse over. Tap the pan a few times so the air bubbles will be released.

    strawberry silicone pan white chocolate mousse
  3. Place it in the freezer for 6 hours, or overnight.

Ganache

  1. Place chopped chocolate, or chocolate chips in a heat proof bowl.
  2. Heat cream in a small saucepan until hot and bubbly. Turn heat off. Pour it over chocolate. Let it sit for 30 seconds. Whisk until chocolate has melted entirely.
  3. Let it cool to room temperature.

Quick chocolate buttercream

  1. Place butter, sifted powdered sugar, sifted cocoa powder, and vanilla in the bowl of an electric mixer. Stir on low until all ingredients are combined. Raise speed and cream on medium high until creamy. Add milk if necessary, if the mixture is too dry or stiff.
  2. Place it in a piping bag so you can pipe on top of your cake.

To assemble Cake

  1. Remove both cakes from the silicone pan. Place the white chocolate mousse cake on top of the hazelnut mousse. Top with ganache.
  2. You can also top it with the simple chocolate buttercream, strawberries, and chocolate truffles.

Storage

  1. This cake will keep well in the fridge for up to 5 days.

Recipe Notes

*Note 1 - I made this brownie a hazelnut brownie. I used the Hazelnut Lindt chocolate bar, which comes with tones of hazelnuts in it. If you don’t have that chocolate, or don’t want to use it, simply use just regular chocolate without adding the hazelnuts. If you desire, add 1/4 cup of chopped hazelnuts to the batter.
**Note 2 - Use any chocolate you would like. Again, I used the Hazelnut Lindt chocolate bar, which is milk chocolate with hazelnuts. You can use milk chocolate, semi-sweet, or dark, according to your preference. Also, you can add about 1/4 cup of chopped hazelnuts to the mousse if you want to add nuts to it but don’t have access to this chocolate bar.
***Note 3 - For the Hazelnut Paste, you will need 1/2 cup of hazelnuts and 3 tablespoons of chocolate chips. Simply add 1/2 cup of hazelnuts to a small blender cup. Process until the hazelnuts are very finely ground turning into a paste, about 5 minutes. Time will vary depending on your food processor. Once the hazelnuts are ground, you can mix them with 3 tablespoons of chocolate chips. Mix until combined. The hazelnuts should be warm enough to melt the chocolate chips. If not, you can place the mixture in the microwave and stir until melted and turned into a paste (a delicious paste, by the way, I won’t judge if you want to eat it with a spoon). If you don’t want to do this, you can use Nutella or another hazelnut spread instead.
****Note 4- If you have a very tall 9” silicone pan, you don’t have to make the two mousses separate. You can make the chocolate mousse on the bottom, and then once it’s frozen and solid, you can pour the white chocolate mousse right on top of it. Just freeze both together and wait for them to be solid. Then you can remove from the pan.

Nutrition Facts
Mousse Cake
Amount Per Serving
Calories 550
* Percent Daily Values are based on a 2000 calorie diet.