Introduction

This Dark Chocolate Mousse Cake is a decadent treat combining a rich chocolate cake base with a silky smooth mousse and a glossy chocolate ganache topping. Perfect for special occasions or whenever you want to impress with a luscious dessert.

The image shows a slice of chocolate cake on a white speckled plate, resting on a white marbled surface. The cake has three layers: the bottom and top layers are dark, moist chocolate sponge with a rough texture, and the middle layer is a lighter, creamy chocolate mousse with a smooth texture. The cake is coated with a thick, glossy chocolate ganache that covers the sides and top, giving it a shiny finish. A silver fork lies on the plate near the cake slice. photo taken with an iphone --ar 4:5 --v 7

Ingredients

Chocolate Cake:

1 Cup (120g) All-Purpose Flour
½ Cup (42g) Dutch Cocoa Powder
1 Teaspoon Fine Espresso Powder (optional, but recommended)
¾ Teaspoon Baking Powder
½ Teaspoon Baking Soda
½ Teaspoon Fine Sea Salt
1 Cup (200g) Granulated White Sugar
⅓ Cup + 1 Tablespoon (80g) Neutral Oil (avocado, vegetable, canola)
⅓ Cup (76g) Full-Fat Sour Cream, room temperature
1 Whole Large Egg, room temperature
1 Teaspoon Pure Vanilla Extract
½ Cup (113g) Boiling Water

Chocolate Mousse:

1½ Cups (340g) Heavy Cream
1 Whole Large Egg + 1 Large Yolk
⅓ Cup (67g) White Granulated Sugar
¼ Cup (21g) Dutch Cocoa Powder
1 Teaspoon Fine Espresso Powder
⅛ Teaspoon Fine Sea Salt
6 Ounces (170g) Dark Chocolate
1 Teaspoon Pure Vanilla Extract
1 Cup (227g) Heavy Cream, cold (to be whipped)

Chocolate Ganache:

5 Ounces (141g) Dark Chocolate (60% to 70% cocoa)
⅔ Cup (151g) Heavy Cream

Instructions

Step 1: Preheat your oven to 350ºF (180ºC). Grease and line a 9-inch (23cm) springform pan with parchment paper.
Step 2: In a small bowl, whisk together the flour, Dutch cocoa powder, espresso powder, baking powder, baking soda, and sea salt.
Step 3: In a large bowl, whisk together sugar, oil, sour cream, egg, and vanilla extract until well combined.
Step 4: Sift the dry ingredients into the wet ingredients, pushing through any cocoa lumps. Gently whisk until nearly combined.
Step 5: Add the boiling water and whisk gently until just combined; the batter will be thin. Pour it into the prepared pan.
Step 6: Bake for 24 to 28 minutes, or until a toothpick inserted in the center comes out clean. Cool in the pan for 15 minutes, then turn out onto a wire rack to cool completely.
Step 7: For the mousse, whisk together heavy cream, whole egg, egg yolk, sugar, cocoa powder, espresso powder, and salt in a saucepan off the heat until combined.
Step 8: Heat the mixture over low heat, whisking constantly until it reaches 170ºF (76ºC), about 8 to 10 minutes.
Step 9: Remove from heat, add chopped dark chocolate and vanilla extract, whisking until smooth. Cover with plastic wrap directly on the surface and chill for 1 to 1.5 hours until thickened.
Step 10: Meanwhile, line the springform pan bottom with parchment paper and place the cooled cake back inside. Wrap the sides with acetate or lightly oiled parchment paper for easy release.
Step 11: Whip the cold heavy cream to firm peaks. Gently fold the chilled chocolate mixture into the whipped cream in two additions until fully combined but not overmixed.
Step 12: Spread the mousse evenly over the cake layer and refrigerate for at least 8 hours to set.
Step 13: To make ganache, finely chop chocolate into a heatproof bowl. Heat heavy cream over medium heat to a low simmer (185ºF / 85ºC).
Step 14: Pour hot cream over chocolate, let sit 4 to 5 minutes, then stir slowly until smooth. If needed, warm gently over simmering water to fully melt the chocolate.
Step 15: Remove the chilled cake from the fridge, unmold it, and remove acetate or parchment sides. Slide it onto a serving plate.
Step 16: Pour ganache on top, spreading to edges. Chill for 10 to 15 minutes to set ganache before slicing and serving. Enjoy!

Tips & Variations

Use fine espresso powder to deepen the chocolate flavor without adding coffee taste.
For a dairy-free version, substitute coconut cream for heavy cream and a suitable vegan chocolate.
Make sure eggs and sour cream are at room temperature for a smoother batter and mousse.
If your mousse mixture hardens too much in the fridge, let it sit briefly at room temperature before folding in whipped cream.
Wrap the cake sides with acetate for clean edges and easy removal of mousse.

Storage

Store the cake covered in the refrigerator for up to 3 days. Keep it chilled to maintain mousse texture. For best results, slice the cake only when ready to serve. Reheat ganache by letting it sit at room temperature a few minutes if it has set too hard.

How to Serve

The image shows a slice of cake on a white plate with small brown specks. The cake has three visible layers: the bottom layer is dark brown and crumbly, the middle layer is a thick light brown mousse-like texture, and the top layer is a smooth, glossy dark chocolate coating that wraps around the sides smoothly. A silver fork rests on the plate in front of the cake slice. The background is a white marbled surface. Photo taken with an iphone --ar 4:5 --v 7

Serve this delicious recipe with your favorite sides.

FAQs

Can I use regular cocoa powder instead of Dutch cocoa powder?

Yes, but Dutch cocoa powder is less acidic and gives a smoother, richer chocolate flavor. Using regular cocoa may result in a slightly different taste and color.

Is it safe to use raw eggs in the mousse?

This recipe cooks the egg mixture to 170ºF (76ºC), which is sufficient to reduce risk by gently pasteurizing the eggs. Use fresh eggs and ensure proper cooking temperature for safety.