Introduction

This Chocolate Mousse Cake is a decadent dessert combining a rich chocolate cake base with silky mousse and a glossy ganache topping. Perfect for special occasions or indulgent treats, it’s a stunning cake that tastes as impressive as it looks.

A rich chocolate cake with three visible layers sits on a white marbled surface; the bottom layer is a dark, dense chocolate cake, the middle layer is a lighter, airy chocolate mousse with a bubbly texture, and the top layer is a smooth, shiny chocolate ganache that covers the entire cake with a glossy finish. One slice is cut and slightly pulled out, showing the clean division between the layers, with a few chocolate shavings scattered near the cake on the surface. The background is dark, making the cake stand out sharply. Photo taken with an iphone --ar 4:5 --v 7

Ingredients

3/4 cup (95g) all-purpose flour (or gluten-free baking flour)
2 tbsp cornstarch
1/4 cup (25g) dutch process cocoa powder
1 tsp baking soda
1/2 tsp baking powder
1/4 tsp kosher salt
1/2 cup (100g) fine granulated sugar
1/2 cup (105g) dark brown sugar, packed
1/2 cup (112g) vegetable or olive oil
2 large eggs
1 tsp vanilla extract
1/2 cup (120g) sour cream
1/2 cup (120g) hot coffee
1 tbsp dutch process cocoa powder (for soaking)
7 oz 70% dark chocolate, chopped
7 oz milk chocolate, chopped
3 large eggs, separated
3 tbsp water
1 1/2 tsp unflavored gelatin
1 3/4 cup heavy cream, divided
1/2 tsp cream of tartar
1/4 cup (50g) fine granulated sugar
6 oz 70% dark chocolate, chopped (for ganache)
3/4 cup (180g) heavy cream (for ganache)

Instructions

Step 1: Preheat the oven to 350°F and grease the inside of a 9″ springform pan. Remove the ring, lay a sheet of parchment paper on the bottom plate, then close the ring back on. Some paper will extend beyond the sides.
Step 2: In a medium bowl, whisk together the flour, cornstarch, cocoa powder, baking soda, baking powder, and salt. Set aside.
Step 3: In a large bowl, whisk the granulated sugar, brown sugar, and oil until it resembles wet sand. Add eggs and vanilla extract, mixing well. Stir in sour cream.
Step 4: Add the dry ingredients to the wet mixture and stir until halfway combined. Pour in the hot coffee and mix until smooth. The batter will be thin.
Step 5: Pour the batter into the prepared pan. Bake for 25–30 minutes or until a toothpick inserted in the center comes out clean with a few moist crumbs. Cool completely at room temperature or in the refrigerator.
Step 6: Once cooled, remove the ring and clean it. Level the top of the cake with a cake leveler or knife. Place the ring back on the pan with the cake inside, then line the pan’s sides with a sheet of acetate or parchment paper as a collar.
Step 7: Stir the hot coffee with the tablespoon of cocoa powder. Spoon this mixture evenly over the cake surface to soak it. Set aside while making the mousse.
Step 8: Place the chopped dark and milk chocolate in a heat-safe bowl. Set over simmering water, ensuring the bowl doesn’t touch the water. Stir until melted and smooth, then remove from heat and let cool slightly.
Step 9: Whisk in egg yolks one at a time into the melted chocolate until the mixture thickens. Meanwhile, sprinkle gelatin over 3 tablespoons of water and let it sit.
Step 10: Heat 3/4 cup heavy cream in a saucepan over medium-low heat until steaming but not boiling. Stir in the bloomed gelatin until dissolved. Remove from heat.
Step 11: Pour half of the hot cream mixture into the chocolate mixture and whisk to combine, then add the rest and whisk again until smooth and glossy.
Step 12: In a clean bowl, whip the remaining 1 cup of heavy cream on high speed until light and fluffy with stiff peaks. Transfer to a separate bowl.
Step 13: Using a clean bowl and whisk, whip the egg whites with cream of tartar. Once foamy, gradually add sugar and continue whipping until soft peaks form.
Step 14: Gently fold the whipped cream into the chocolate mixture until combined. Then fold in the meringue carefully until the mousse is uniform and pourable.
Step 15: Pour the mousse over the soaked cake and refrigerate for at least 4 hours, preferably overnight, to set.
Step 16: Remove the ring and peel off the acetate collar. For the ganache, heat the heavy cream until hot and bubbling, then pour it over the chopped dark chocolate. Let sit 3 minutes and whisk until smooth.
Step 17: Pour the ganache over the center of the mousse layer and spread gently to the edges, allowing drips down the sides. Chill the cake for at least 30 minutes to set the ganache.
Step 18: Slice and enjoy your rich, elegant Chocolate Mousse Cake!

Tips & Variations

Use gluten-free flour to make this cake gluten-free without sacrificing texture.
Substitute brewed espresso for hot coffee for a deeper chocolate flavor.
Line the pan with parchment paper instead of acetate if acetate is not available, but acetate helps with a smooth mousse edge.
For a lighter mousse, fold in whipped egg whites gently but thoroughly to maintain airiness.

Storage

Store the Chocolate Mousse Cake covered in the refrigerator for up to 3 days. Keep it chilled to maintain mousse texture and ganache gloss. To serve, you can let it sit at room temperature for 10–15 minutes for easier slicing. Do not freeze as it may affect the delicate mousse texture.

How to Serve

The image shows a rich, layered chocolate cake resting on brown parchment paper and a wooden board with deep texture. The cake has three main layers: a dark, dense bottom layer resembling a chocolate crust, a thick middle layer of light and airy chocolate mousse with a rough texture, and a smooth, glossy dark chocolate ganache dripping down the sides in thick drips. The background is dark, making the cake stand out sharply. The photo taken with an iphone --ar 4:5 --v 7

Serve this delicious recipe with your favorite sides.

FAQs

Can I make this cake ahead of time?

Yes, it’s ideal to prepare the cake the day before serving to allow the mousse to set fully and for flavors to meld.

Can I use regular granulated sugar instead of fine granulated sugar?

You can, but fine sugar dissolves better in the meringue and batter, resulting in a smoother texture. If using regular sugar, consider pulsing it briefly in a food processor to make it finer.