Triple Chocolate Mousse Cake Recipe

This triple chocolate mousse cake is three layers of mousse, dark, milk and white chocolate, set one on top of the other over a thin cocoa sponge in a 9 inch springform pan. It serves 12 and takes about 5 hours from start to slicing, and most of that is fridge time.

Every mousse layer is made the same way, so once you have done the dark one, the other two go quickly. The step that decides whether the layers come out smooth is the fold: the chocolate base has to be lukewarm, not hot and not cold, when the whipped cream goes in.

One Formula, Three Layers

Each layer uses exactly the same amounts. Only the chocolate changes.

• Chocolate: 100 g, finely chopped (dark 60 to 70%, then milk, then white)
• Hot liquid: ½ cup (120 ml) heavy cream plus ¼ cup (60 ml) milk, heated until steaming
• Gelatin: 1 teaspoon powdered gelatin bloomed in 1 tablespoon cold water
• Whipped part: ½ cup (120 ml) cold heavy cream, whipped to soft peaks
• Chill between layers: 30 to 45 minutes; at least 4 hours after the last one

The hot cream and milk melt the chocolate into a thin, pourable base, a loose chocolate ganache. The milk is what keeps it loose enough to take the whipped cream without streaks. One teaspoon of gelatin per layer is just enough to let the mousse hold a clean edge when sliced, while it still feels creamy on the spoon.

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Baking the Thin Cocoa Sponge Base

Heat the oven to 175°C (350°F) and line the bottom of the springform with parchment. Beat the 2 eggs with the sugar for about 4 minutes, until pale and thick enough to leave a trail. Mix in the milk, oil and vanilla, then sift over the flour, cocoa, baking powder and salt and fold gently until no dry streaks remain.

Bake for 12 to 15 minutes, until a toothpick comes out clean. With only ⅓ cup of flour the sponge is thin and soft, which is what you want under three layers of mousse. A thick cake would take over every bite.

Let it cool completely, then lift it out, wash and dry the pan, and set the sponge back inside the closed ring. For straight, sharp sides, line the ring with an acetate collar first. Strips of parchment work too if you trim them cleanly. Check that the pan sits level in the fridge, or each layer sets on a slope.

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Dark, Milk and White: How Each Layer Behaves

The dark layer goes first and sets the firmest. A 60 to 70% chocolate keeps it bittersweet, so the sweeter layers above it have something to lean against. Chop it finely; chunks do not melt fully in the warm cream and leave specks.

Milk chocolate makes a softer, paler middle layer that bridges the bitter bottom and the sweet top. It melts at a lower temperature than dark, so it smooths out quickly once the cream goes over it.

White chocolate is the fussy one. It has the most sugar and milk solids, so it scorches if the cream is boiling and can turn greasy. Heat the cream and milk only until steam rises, let the white chocolate sit for a full minute before stirring, and choose a brand that lists cocoa butter as an ingredient. The white layer also sets the softest of the three, which is one more reason it goes on top.

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Blooming the Gelatin and Folding at the Right Temperature

Sprinkle the gelatin over the cold water and leave it for 5 minutes. It turns into a thick, spongy gel. Heat the cream and milk until steaming, take the pan off the heat, and stir in the gel until no grains are left. Pour it over the chopped chocolate, wait a minute, then stir from the middle out until glossy.

Now let it cool until it feels barely warm on the inside of your wrist, close to body temperature. This takes 10 to 15 minutes. Too hot, and the whipped cream melts and the mousse turns thin and sinks. Too cold, and the gelatin starts to set, so the cream folds into lumps.

While it cools, whip the cold cream to soft peaks: the peak slumps over when you lift the whisk. Stiff cream looks safer, but it folds in grainy and leaves streaks. Stir a third of the cream in to loosen the base, then fold in the rest with a spatula until no white streaks show. The same fold is behind this chocolate mousse filling for cakes.

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Is the Layer Set? The Fingertip Test

After 30 minutes in the fridge, touch the center lightly. The layer is ready when the surface feels firm and your fingertip comes away clean, with no mark left behind. If it still wobbles or sticks, give it another 10 to 15 minutes.

Pour the next mousse over the back of a large spoon held just above the surface. It spreads gently instead of punching a hole in the layer below. Smooth it with an offset spatula and go straight back to the fridge.

Make each mousse only when the layer before it is nearly set. A mousse that waits too long on the counter starts to thicken in the bowl and will not spread flat.

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A Timeline From Morning to Dessert

• Start: bake the sponge (15 minutes) and let it cool completely
• Then: make the dark mousse, pour, chill 30 to 45 minutes
• Next: make the milk chocolate mousse, pour, chill 30 to 45 minutes
• Last: make the white chocolate mousse, pour, chill at least 4 hours

Plan about 5 hours in total, or make the whole cake the day before. It slices more cleanly on day two, after a night in the fridge.

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Clean Slices and Chocolate Curls

Run a warm knife around the inside of the ring, open the springform and peel away the acetate. Top with chocolate curls, shavings, or a light dusting of cocoa powder. Plain is fine too, since the stripes show on every slice.

Cut it straight from the fridge with a long, sharp knife dipped in hot water and wiped dry between every cut. A cold cake and a hot, clean blade give the three sharp stripes you see in the photo. Serve the slices within 30 minutes; mousse softens quickly at room temperature.

For a single layer version, try this chocolate mousse cake. The same three chocolates also go into individual triple chocolate mousse domes, and if you like mousse on a fudgy base, chocolate mousse brownies are the quicker bake.

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Layered Mousse Cake Questions

Can I make it without gelatin?

Yes, with agar powder. Use about half the amount, ½ teaspoon per layer, and boil it in the cream and milk for 1 to 2 minutes. Agar sets as soon as it cools, so fold in the whipped cream quickly. The mousse will be firmer and less creamy.

Can I use double cream in the UK?

Yes. Double cream whips faster than heavy cream, so watch it and stop at soft peaks. All the mousse amounts are already in grams and millilitres.

How long does the cake keep?

Covered in the fridge, up to 3 days. It also freezes for up to 1 month: freeze it uncovered until firm, wrap it well, and thaw overnight in the fridge before slicing.

Can I use a different pan size?

An 8 inch springform gives taller layers and a slightly thicker sponge; add a few minutes to the bake. For a fuller chocolate frosting on another layer cake, see this chocolate ganache frosting.