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Close up of a slice of chocolate mousse cake on a plate.

Most Amazing Chocolate Mousse Cake

This incredible chocolate mousse cake is made with moist chocolate cake, light and creamy eggless chocolate mousse, and a silky chocolate ganache.
5 from 3 votes
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Prep Time 50 minutes
Cook Time 25 minutes
chill time 5 hours
Total Time 6 hours 15 minutes
Course Dessert
Cuisine French
Servings 10 slices
Calories 651 kcal

Ingredients
 
 

For the chocolate cake

  • ¾ cup Granulated sugar
  • 1 teaspoon Vanilla extract
  • ¼ teaspoon Kosher salt
  • ⅓ cup Vegetable oil
  • 1 Egg
  • 1 Egg yolk
  • ⅓ cup Sour cream
  • ⅓ cup Buttermilk
  • ⅓ cup Cocoa powder Dutch processed
  • 1 cup Flour AP, plain flour
  • ¼ teaspoon Baking soda
  • 1 teaspoon Baking powder
  • ½ cup Coffee hot

For the chocolate mousse

Melt together:

  • 7.05 oz Dark chocolate 60%
  • 4.2 oz heavy cream

Whip together

  • 1 ¾ cups Heavy cream cold
  • 1 teaspoon Vanilla extract
  • 2 tablespoon Cocoa powder Dutch processed
  • 3 tablespoon Powdered sugar

Gelatin:

  • 7 g Gelatin powder
  • 42 g Water

For the chocolate ganache

  • 5.2 oz Heavy cream
  • 5.2 oz Dark chocolate

Instructions
 

Bake the One-Bowl Chocolate Cake Base

  • Preheat your oven to 180°C (350°F). Line a 9-inch springform pan with parchment paper and grease with cooking spray.
  • In a large mixing bowl, combine the eggs, buttermilk, oil, vanilla extract, kosher salt, granulated sugar, and sour cream. Sift in ½ of the cocoa powder and whisk until completely smooth.
  • Sift the flour into the bowl, add the baking powder and baking soda, and whisk until almost combined.
  • In a separate cup, stir the remaining half of the cocoa powder into the hot coffee to bloom it. Pour this hot coffee mixture into your main batter bowl and gently stir until smooth, fluid, and free of lumps.
  • Pour the chocolate batter into your prepared pan. Bake for 22–25 minutes. The cake is done when a toothpick inserted into the center comes out clean with just a few moist crumbs.
  • Transfer the pan to a wire rack and let the cake cool completely to room temperature.

Create the Stabilized Chocolate Mousse

  • In a small bowl, mix the water and unflavored gelatin powder. Let it sit for 10 minutes to bloom and thicken.
  • In a large mixing bowl, combine the eggs, buttermilk, oil, vanilla extract, kosher salt, granulated sugar, and sour cream. Sift in the first half of the cocoa powder and whisk until completely smooth.
  • Whisk the melted chocolate and cream vigorously or use an immersion blender until the mixture is shiny, smooth, and perfectly emulsified.
  • In a separate large mixing bowl, combine the cold heavy cream, sifted cocoa powder, powdered sugar, and vanilla extract. Whip until it reaches soft peaks with a thick, yogurt-like consistency.
  • Microwave the bloomed gelatin for 5 seconds until fluid (do not overheat!). Whisk the melted gelatin into your warm chocolate mixture.
  • Stir ½ cup of your whipped cream into the chocolate base to lighten it.
  • Gently fold the remaining chocolate mixture into the whipped cream in two separate batches using a rubber spatula. Fold just until homogeneous and streak-free to retain maximum air.
  • Release the cooled cake from the springform ring. Use a serrated knife or cake leveler to trim off any unevenness on the top so it is perfectly flat.
  • Place the leveled cake back into the clean springform pan. Slide a sheet of acetate cake collar down the sides of the pan, wedging it gently between the cake and the pan wall. Ensure the collar extends about an inch above the pan rim.
  • Pour the fluffy chocolate mousse directly over the cake layer. Smooth the surface with an offset spatula and refrigerate for at least 5 hours, or ideally overnight, to set.
  • Combine dark chocolate and heavy cream in a small bowl and microwave for 70 seconds. Let it sit undisturbed for 10 minutes, then stir gently until a glossy, silky ganache forms.
  • Release the springform ring and gently peel away the acetate collar.
  • Pour the slightly warm ganache directly onto the center of the chilled cake. Use your offset spatula to nudge it elegantly over the edges.
  • Return the cake to the fridge for 30 minutes to let the ganache set. Slice with a warm knife and enjoy!

Notes

  • Use Neutral Oils Only: Select flavorless oils like canola, safflower, or sunflower oil. Avoid olive or coconut oils, which leave strong aftertastes that mask the rich chocolate flavor.
  • Do Not Reduce the Sugar: Sugar functions as a liquid tenderizer and hydrator. Reducing the amount will alter the chemical structure, resulting in a dry, crumbly cake base once chilled.
  • Test for Moist Crumbs: Start checking the cake 2 minutes before the baking time ends. A toothpick inserted into the center should come out with a few damp, clinging crumbs—not completely clean, which indicates overbaking.
  • Stir the Ganache Slowly: Mix the melted cream and chocolate gently with a rubber spatula. Vigorous whisking incorporates air pockets and forces the cocoa butter to separate, creating a dull, greasy glaze.
  • Whip Cream to Medium Peaks: Stop whipping the heavy cream when it reaches a thick, yogurt-like consistency. Over-whipped, stiff cream loses its elasticity and turns grainy when folded into the chocolate base.

Nutrition

Calories: 651kcalCarbohydrates: 48gProtein: 8gFat: 50gSaturated Fat: 27gPolyunsaturated Fat: 6gMonounsaturated Fat: 13gTrans Fat: 0.1gCholesterol: 119mgSodium: 173mgPotassium: 421mgFiber: 6gSugar: 26gVitamin A: 1128IUVitamin C: 0.5mgCalcium: 123mgIron: 6mg
Keyword Chocolate Mousse Cake
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