A magnificent cake filled with three layers of chocolate flavor and a silky texture!

Why You’ll Love This Recipe

It has three distinct chocolate layers — a moist chocolate cake base, a light and airy chocolate mousse filling, and a glossy ganache topping.
Each bite offers a balance of rich flavor and creamy texture.
Perfect for special occasions or when you want to impress guests.
Can be prepared ahead of time and chilled for convenience.
Ideal for true chocolate lovers who enjoy a smooth, decadent dessert.

Ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

Chocolate Cake Base:

1 cup (133 g) all-purpose flour
¾ cup (150 g) granulated sugar
⅓ cup (30 g) unsweetened cocoa powder
1 teaspoon baking soda
½ teaspoon baking powder
¼ teaspoon salt
¼ cup (60 ml) vegetable oil
1 large egg (room temperature)
1 teaspoon pure vanilla extract
½ cup (120 ml) full-fat buttermilk (room temperature)
½ cup (120 ml) hot coffee or hot water

Chocolate Mousse Filling:

2 cups (370 g) semi-sweet chocolate chips
2 ⅓ cups (560 ml) heavy whipping cream, divided
2 tablespoons powdered sugar
2 teaspoons pure vanilla extract

Chocolate Ganache Topping:

½ cup (93 g) semi-sweet chocolate chips
½ cup (120 ml) heavy whipping cream

Directions

Preheat oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.
In a bowl, whisk flour, sugar, cocoa powder, baking soda, baking powder, and salt.
Add oil, egg, vanilla, buttermilk, and hot coffee (or water). Mix until smooth; the batter will be thin.
Pour into prepared pan and bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean. Cool completely.
For the mousse, melt the chocolate chips using a microwave or double boiler, then cool slightly.
Whip the heavy cream with powdered sugar and vanilla until soft peaks form. Fold one-third of the whipped cream into the melted chocolate to lighten it, then gently fold in the rest until smooth. Chill until slightly firm.
Place the cake on a serving plate. Spread a thick layer of mousse over it. If you made two layers, repeat cake → mousse → cake. Chill for at least 30 minutes.
For the ganache, heat the cream until just simmering. Pour over the chocolate chips and let sit for 2 minutes. Whisk until glossy and smooth. Cool until pourable.
Pour ganache over the chilled cake, allowing it to drip down the sides. Chill for 30 minutes to set before serving.

Servings and timing

Servings: 12 slices
Prep time: 20 minutes
Baking time: 30–35 minutes
Cooling and chilling time: 1–2 hours
Total time: approximately 2 hours

Variations

Use dark chocolate (70% cocoa) instead of semi-sweet for a more intense flavor.
Add a thin layer of raspberry jam or sliced strawberries between layers.
Make it gluten-free by substituting a gluten-free flour blend.
Replace the ganache with chocolate whipped cream for a lighter finish.
Decorate with chocolate curls, cocoa powder, or fresh berries.

Storage/Reheating

Store covered in the refrigerator for up to 5–7 days.
Bring to room temperature for 20–30 minutes before serving.
Freeze slices individually wrapped in foil for up to 3 months. Thaw in the refrigerator overnight before serving.

FAQs

What if I don’t have buttermilk?

Mix ½ cup milk with ½ tablespoon lemon juice or vinegar and let sit for 5 minutes before using.

Can I make the mousse without heavy cream?

Heavy cream is essential for structure; substitutes may cause the mousse to collapse.

Do I need a springform pan?

It’s helpful but not necessary. A regular round pan lined with parchment works fine.

Can I skip the ganache?

Yes, but the ganache adds richness and a beautiful glossy finish.

How far in advance can I make this cake?

You can assemble it up to 24 hours before serving; keep it chilled.

What chocolate gives the best flavor?

Use high-quality semi-sweet or dark chocolate for the best taste and texture.

Can I halve the recipe?

Yes, halve all ingredients and bake in an 8-inch pan; adjust baking time slightly.

Is the coffee necessary?

No — it enhances the chocolate flavor but can be replaced with hot water.

How do I get clean slices?

Warm a sharp knife in hot water, dry it, and slice. Clean between cuts.

Can I make it vegan?

Use plant-based milk, vegan chocolate, and coconut cream instead of dairy ingredients.

Conclusion

This Chocolate Mousse Layer Cake is the ultimate indulgence for chocolate lovers. With its rich cake base, velvety mousse, and smooth ganache topping, it’s a dessert that looks elegant and tastes divine. Whether for a celebration or a cozy evening treat, it’s guaranteed to impress and satisfy every sweet craving.

Chocolate Mousse Layer Cake