I made a Chocolate Mousse Cake with dark cocoa powder, an easy chocolate mousse filling, and a glossy ganache, and I’ll share the single trick that keeps the layers perfectly in place.

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I love recipes that tease you before the first bite and this Dark Chocolate Mousse Cake does just that. The cake layer is stained with unsweetened dark cocoa powder so every forkful hits deep chocolate notes, while a pillowy mousse made from good quality dark chocolate, chopped for the mousse, slips between the layers like a secret.

It looks formal but it’s kinda mischievous, the kind of dessert that makes people raise an eyebrow and ask what you used, then refuse to tell. If you like drama in your desserts try this Chocolate Mousse Cake, you might not go back.

Ingredients

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All purpose flour Adds structure and carbs low in fiber so not very filling but cheap
Unsweetened dark cocoa powder Deep chocolate taste, some fiber and antioxidants, bitter not sweet
Eggs Give protein and richness, help bind and leaven, add moisture and savory notes
Whole milk Adds fat and calcium, makes batter tender, adds lactose for slight sweetness
Heavy whipping cream for mousse Rich fat makes silky mousse, adds calories, gives whipped body if chilled
Dark chocolate for mousse and ganache High cocoa gives intense flavor, some antioxidants, adds fat and depth
Hot coffee Enhances chocolate flavor, adds no sweetness, can mask bitterness and deepen cocoa notes

Ingredient Quantities

1 3/4 cups (220 g) all purpose flour

3/4 cup (75 g) unsweetened dark cocoa powder

2 cups (400 g) granulated sugar

1 1/2 tsp baking powder

1 1/2 tsp baking soda

1 tsp salt

2 large eggs, room temp

1 cup (240 ml) whole milk

1/2 cup (120 ml) vegetable oil

2 tsp vanilla extract

1 cup (240 ml) hot strong coffee or hot water

8 oz (225 g) good quality dark chocolate, chopped for the mousse

1 1/2 cups (360 ml) heavy whipping cream, cold, divided

2 tbsp granulated sugar (for mousse)

1 tsp vanilla extract (for mousse)

1 tbsp powdered gelatin plus 3 tbsp cold water, optional for extra-stable mousse

8 oz (225 g) dark chocolate, chopped for the ganache

1 cup (240 ml) heavy cream for the ganache

2 tbsp unsalted butter, room temp, optional for shine

pinch of salt

How to Make this

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1. Preheat oven to 350 F (175 C). Grease and line two 8 inch round pans, or one 9 inch if thats what you have, then dust lightly with a little flour or cocoa. Whisk together 1 3/4 cups (220 g) all purpose flour, 3/4 cup (75 g) unsweetened dark cocoa powder, 2 cups (400 g) granulated sugar, 1 1/2 tsp baking powder, 1 1/2 tsp baking soda and 1 tsp salt in a big bowl.

2. In another bowl whisk 2 large eggs (room temp), 1 cup (240 ml) whole milk, 1/2 cup (120 ml) vegetable oil and 2 tsp vanilla extract until smooth. Pour wet into dry and mix until just combined, dont overmix.

3. Stir in 1 cup (240 ml) hot strong coffee or hot water; batter will be thin, thats okay. Divide between pans and bake 30 to 35 minutes (25 to 30 for 9 inch) or until a toothpick comes out with a few moist crumbs. Cool in pans 10 minutes then turn out to a rack to cool completely.

4. Make the mousse: chop 8 oz (225 g) good quality dark chocolate. Heat 1/2 cup of the heavy whipping cream (from the 1 1/2 cups) until steaming but not boiling, pour over the chopped chocolate and let sit 1 minute, then stir until smooth. Optional for extra-stable mousse: sprinkle 1 tbsp powdered gelatin over 3 tbsp cold water, let bloom 5 minutes then gently warm (microwave 10 seconds or over simmering water) until dissolved and whisk into the melted chocolate.

5. Whip the remaining 1 cup (240 ml) cold heavy whipping cream with 2 tbsp granulated sugar and 1 tsp vanilla extract to soft to medium peaks. Let the melted chocolate cool just a bit so it is warm not hot, then fold about a third of the whipped cream into the chocolate to lighten it, then fold in the rest gently until homogenous. Chill briefly if it seems too loose.

6. Level your cake layers if needed. Place one layer on a cake plate, mound or pipe the mousse evenly to about 3/4 inch to 1 inch thick (or thicker if you like), then top with the second layer. Press gently, cover and chill at least 1 hour to let mousse set; longer is better.

7. Make the ganache: chop 8 oz (225 g) dark chocolate. Heat 1 cup (240 ml) heavy cream until just simmering, pour over chocolate, let sit 1 minute then stir until silky smooth. Stir in 2 tbsp unsalted butter (room temp) if you want extra shine and a pinch of salt to brighten flavor. Let ganache cool until slightly thickened but still pourable, about 10 to 20 minutes in the fridge, stirring occasionally.

8. Pour ganache over the chilled cake, letting it spill down the sides; use a spatula to smooth if needed. If you want clean edges, pour slowly from the center and use a small offset spatula to pull the glaze to the edge. Return cake to fridge for at least 1 hour so ganache and mousse fully set.

9. Serve chilled or at cool room temperature. Store in fridge up to 3 days, but bring out 20 minutes before serving so the textures open up. Quick tips: use room temp eggs for lighter crumb, dont overbeat the whipped cream, warm the coffee to bloom the cocoa for deeper chocolate flavor, and if you used gelatin your mousse will slice cleaner.

Equipment Needed

1. Oven preheated to 350 F (175 C), obviously get it ready first
2. Two 8 inch round cake pans or one 9 inch, plus parchment rounds and something to grease them
3. Mixing bowls, at least one large for dry and one medium for wet
4. Measuring cups, spoons and a kitchen scale for accuracy (really helps)
5. Whisk and rubber spatula for mixing and folding
6. Electric mixer (hand or stand) for whipping the cream, or be ready to arm-whip it if you must
7. Heatproof bowl plus a small saucepan for melting chocolate over simmering water or use a microwave safe bowl
8. Offset spatula and serrated knife for leveling and smoothing the cake
9. Cooling rack and a toothpick for testing doneness

FAQ

Q: Can I make the cake ahead of time?
A: Yes. Bake the layers 1-2 days ahead and keep wrapped at room temp or in the fridge. The mousse and assembly are best done the day you serve but you can assemble 1 day ahead and chill overnight for cleaner slices. For longer storage freeze wrapped layers or the whole assembled cake up to 1 month, thaw in the fridge overnight.

Q: Do I need the gelatin for the mousse?
A: No, you dont have to use it. Good chocolate, very cold cream whipped to medium-stiff peaks, and gentle folding will give a nice mousse. Use the 1 tbsp powdered gelatin bloomed in 3 tbsp cold water if you want extra-stable mousse for hot climates or if you need it to hold perfect shape for a long time.

Q: What chocolate should I use for mousse and ganache?
A: Use good quality dark chocolate, about 60-70% cocoa for a balanced bitter-sweet flavor. Avoid chocolate chips, chop bars finely so they melt smoothly. Two different batches of the same quality work fine, but dont skimp on chocolate here, it really shows.

Q: Why did my cake turn out dry or dense?
A: Most likely overmixing or overbaking, or measuring flour too tightly. Spoon and level the flour, dont pack it. Mix just until combined, and watch bake time closely, test with a toothpick. The hot coffee in the recipe helps keep it moist so dont skip it.

Q: How do I get a shiny, smooth ganache?
A: Heat cream until just simmering, pour over chopped chocolate and let sit 1-2 minutes before stirring from the center in slow circles. Add the butter at the end for extra shine. Cool until pourable but not hot, pour over chilled cake for a glassy finish.

Q: Best way to slice clean pieces?
A: Chill the cake until mousse and ganache are firm, use a long sharp knife dipped in hot water, wipe dry between cuts. Cutting with a steady sawing motion and cleaning the blade between slices gives neat edges.

Dark Chocolate Mousse Cake Recipe Substitutions and Variations

All purpose flour: swap for cake flour or a 1 to 1 gluten free blend or whole wheat pastry flour. To make cake flour from AP, replace 2 tbsp cornstarch per cup of flour and sift, or just use cake flour by weight. If you pick a gluten free blend, use cup for cup but add 1 tsp xanthan gum if your blend lacks it, expect a slightly crumbly crumb.
Unsweetened dark cocoa powder: you can use natural unsweetened cocoa or Dutch process cocoa. If you switch to Dutch process and keep the baking soda, rise may change so either use baking powder instead or accept a denser crumb but darker flavor. Another quick trick is to replace 3 tbsp cocoa with 1 oz melted dark chocolate for extra depth.
Eggs (2 large): use 2 flax eggs (2 tbsp ground flaxseed mixed with 6 tbsp water, let sit 5 min), or 1/2 cup silken tofu blended for both eggs, or 1/2 cup unsweetened applesauce for a moister denser cake. Heads up these plant swaps give less lift and a bit more chew, dont expect exactly the same texture as with eggs.
Heavy cream for mousse or ganache: swap with chilled full fat coconut cream for a dairy free version, or fold mascarpone into lightly whipped cream for more stability. For ganache you can also use evaporated milk for a lighter finish, or use equal parts chopped chocolate and a non dairy cream alternative, warming gently until smooth.

Pro Tips

1) Use really hot coffee to bloom the cocoa and deepen the chocolate flavor, but dont let it be scalding when you mix it into the batter or chocolate or you’ll risk seizing. Strong brewed coffee or espresso works great, even a splash will amp the chocolate without tasting like coffee.

2) Chill your bowl and beaters and whip the cream to soft to medium peaks only, then fold in gently in thirds with a wide spatula using a sweeping motion so you keep as much air as possible. Overwhipping or aggressive folding will make the mousse go flat, so be patient and stop as soon as it’s uniform.

3) If you want extra-stable mousse use the gelatin trick, but bloom it properly and warm just enough to dissolve before whisking into the melted chocolate, let the chocolate cool a bit before combining with whipped cream or the heat will collapse the air. If you skip gelatin, make sure the mousse chills long enough to firm up before you stack and glaze.

4) For a shiny, smooth ganache pour it when slightly thickened and still pourable, pour from the center and coax to the edges with an offset spatula for clean coverage. Chill the whole cake until set, and for neat slices warm a sharp knife under hot water, wipe dry between cuts and slice confidently so the mousse and ganache dont smear.

Dark Chocolate Mousse Cake Recipe

Recipe by Samantha Dalling

0.0 from 0 votes

I made a Chocolate Mousse Cake with dark cocoa powder, an easy chocolate mousse filling, and a glossy ganache, and I’ll share the single trick that keeps the layers perfectly in place.

Servings

servings

Calories

725

kcal

Equipment: 1. Oven preheated to 350 F (175 C), obviously get it ready first
2. Two 8 inch round cake pans or one 9 inch, plus parchment rounds and something to grease them
3. Mixing bowls, at least one large for dry and one medium for wet
4. Measuring cups, spoons and a kitchen scale for accuracy (really helps)
5. Whisk and rubber spatula for mixing and folding
6. Electric mixer (hand or stand) for whipping the cream, or be ready to arm-whip it if you must
7. Heatproof bowl plus a small saucepan for melting chocolate over simmering water or use a microwave safe bowl
8. Offset spatula and serrated knife for leveling and smoothing the cake
9. Cooling rack and a toothpick for testing doneness

Ingredients

1 3/4 cups (220 g) all purpose flour
3/4 cup (75 g) unsweetened dark cocoa powder
2 cups (400 g) granulated sugar
1 1/2 tsp baking powder
1 1/2 tsp baking soda
1 tsp salt
2 large eggs, room temp
1 cup (240 ml) whole milk
1/2 cup (120 ml) vegetable oil
2 tsp vanilla extract
1 cup (240 ml) hot strong coffee or hot water
8 oz (225 g) good quality dark chocolate, chopped for the mousse
1 1/2 cups (360 ml) heavy whipping cream, cold, divided
2 tbsp granulated sugar (for mousse)
1 tsp vanilla extract (for mousse)
1 tbsp powdered gelatin plus 3 tbsp cold water, optional for extra-stable mousse
8 oz (225 g) dark chocolate, chopped for the ganache
1 cup (240 ml) heavy cream for the ganache
2 tbsp unsalted butter, room temp, optional for shine
pinch of salt

Directions

Preheat oven to 350 F (175 C). Grease and line two 8 inch round pans, or one 9 inch if thats what you have, then dust lightly with a little flour or cocoa. Whisk together 1 3/4 cups (220 g) all purpose flour, 3/4 cup (75 g) unsweetened dark cocoa powder, 2 cups (400 g) granulated sugar, 1 1/2 tsp baking powder, 1 1/2 tsp baking soda and 1 tsp salt in a big bowl.
In another bowl whisk 2 large eggs (room temp), 1 cup (240 ml) whole milk, 1/2 cup (120 ml) vegetable oil and 2 tsp vanilla extract until smooth. Pour wet into dry and mix until just combined, dont overmix.
Stir in 1 cup (240 ml) hot strong coffee or hot water; batter will be thin, thats okay. Divide between pans and bake 30 to 35 minutes (25 to 30 for 9 inch) or until a toothpick comes out with a few moist crumbs. Cool in pans 10 minutes then turn out to a rack to cool completely.
Make the mousse: chop 8 oz (225 g) good quality dark chocolate. Heat 1/2 cup of the heavy whipping cream (from the 1 1/2 cups) until steaming but not boiling, pour over the chopped chocolate and let sit 1 minute, then stir until smooth. Optional for extra-stable mousse: sprinkle 1 tbsp powdered gelatin over 3 tbsp cold water, let bloom 5 minutes then gently warm (microwave 10 seconds or over simmering water) until dissolved and whisk into the melted chocolate.
Whip the remaining 1 cup (240 ml) cold heavy whipping cream with 2 tbsp granulated sugar and 1 tsp vanilla extract to soft to medium peaks. Let the melted chocolate cool just a bit so it is warm not hot, then fold about a third of the whipped cream into the chocolate to lighten it, then fold in the rest gently until homogenous. Chill briefly if it seems too loose.
Level your cake layers if needed. Place one layer on a cake plate, mound or pipe the mousse evenly to about 3/4 inch to 1 inch thick (or thicker if you like), then top with the second layer. Press gently, cover and chill at least 1 hour to let mousse set; longer is better.
Make the ganache: chop 8 oz (225 g) dark chocolate. Heat 1 cup (240 ml) heavy cream until just simmering, pour over chocolate, let sit 1 minute then stir until silky smooth. Stir in 2 tbsp unsalted butter (room temp) if you want extra shine and a pinch of salt to brighten flavor. Let ganache cool until slightly thickened but still pourable, about 10 to 20 minutes in the fridge, stirring occasionally.
Pour ganache over the chilled cake, letting it spill down the sides; use a spatula to smooth if needed. If you want clean edges, pour slowly from the center and use a small offset spatula to pull the glaze to the edge. Return cake to fridge for at least 1 hour so ganache and mousse fully set.
Serve chilled or at cool room temperature. Store in fridge up to 3 days, but bring out 20 minutes before serving so the textures open up. Quick tips: use room temp eggs for lighter crumb, dont overbeat the whipped cream, warm the coffee to bloom the cocoa for deeper chocolate flavor, and if you used gelatin your mousse will slice cleaner.

Notes

Below you’ll find my best estimate of this recipe’s nutrition facts. Treat the numbers as a guide rather than a rule—great food should nourish both body and spirit. Figures are approximate, and the website owner assumes no liability for any inaccuracies in this recipe.