No-Bake Chocolate Hazelnut Mousse Cake

This no-bake chocolate hazelnut mousse cake combines a crunchy chocolate biscuit base, a smooth hazelnut cheesecake layer and a glossy dark chocolate ganache topping. Rich without being excessively sweet, it is an elegant dessert for birthdays, dinner parties or special family gatherings.

The cake does not require an oven, but it needs enough time in the refrigerator for each layer to become firm. Preparing it the day before serving gives the best texture and makes slicing much easier.

For a deeper flavour, toast the hazelnuts before using them. Toasting brings out their natural sweetness and creates a pleasant contrast with the creamy filling and dark chocolate topping.

Recipe

Preparation time

35 minutes

Chilling time

At least 6 hours

Servings

10–12 slices

Ingredients

For the chocolate biscuit base

• 250 g chocolate biscuits
• 90 g unsalted butter, melted
• 30 g toasted hazelnuts
• A small pinch of salt

For the hazelnut mousse filling

• 500 g full-fat cream cheese, at room temperature
• 250 g chocolate hazelnut spread
• 80 g icing sugar
• 1 teaspoon vanilla extract
• A small pinch of salt
• 300 ml double cream or heavy cream, cold
• 7 g powdered gelatine
• 3 tablespoons cold water

For the chocolate ganache

• 180 g dark chocolate, finely chopped
• 150 ml double cream or heavy cream
• 15 g unsalted butter

For decoration

• 70 g toasted hazelnuts, roughly chopped
• Chocolate curls or grated dark chocolate
• A small pinch of flaky sea salt, optional

Instructions

1. Prepare the cake tin

Line the base of a 20 cm springform tin with baking paper.

Lightly grease the sides or line them with acetate cake film. Acetate helps create clean, smooth edges when the cake is removed from the tin.

2. Make the biscuit base

Place the chocolate biscuits and toasted hazelnuts in a food processor. Blend until they form fine crumbs.

Add the melted butter and salt, then pulse again until the mixture resembles damp sand.

Transfer the mixture to the prepared tin. Press it firmly and evenly across the base using the bottom of a glass or measuring cup.

Refrigerate the base for at least 30 minutes while preparing the filling.

3. Bloom the gelatine

Place three tablespoons of cold water in a small bowl.

Sprinkle the powdered gelatine evenly over the water. Leave it to stand for approximately five minutes, until it becomes soft and absorbs the liquid.

Do not add dry gelatine directly to the filling, as this may create small lumps.

4. Prepare the hazelnut mixture

Place the cream cheese, chocolate hazelnut spread, icing sugar, vanilla extract and salt in a large mixing bowl.

Beat on low to medium speed until the mixture is smooth and evenly combined. Scrape down the sides of the bowl when necessary.

Avoid overmixing, as excessive air can make the finished cake less stable.

5. Dissolve the gelatine

Warm the bloomed gelatine gently in the microwave for approximately 10 seconds, or place the bowl over warm water.

Stir until the gelatine becomes completely liquid. It should be warm but not boiling.

Add two tablespoons of the hazelnut mixture to the dissolved gelatine and stir well. This helps bring the ingredients to a similar temperature and prevents the gelatine from setting too quickly.

Pour the gelatine mixture into the main bowl and mix until fully incorporated.

6. Whip the cream

Pour the cold double cream into a separate bowl.

Whip until medium peaks form. The cream should hold its shape while remaining smooth and slightly soft.

Fold one-third of the whipped cream into the hazelnut mixture to lighten it. Gently fold in the remaining cream using a spatula.

Mix only until no white streaks remain.

7. Assemble the cake

Remove the chilled biscuit base from the refrigerator.

Spoon the hazelnut mousse filling over the base and spread it into an even layer. Smooth the surface with a spatula.

Cover the tin and refrigerate for at least four hours, or until the filling feels firm.

8. Prepare the chocolate ganache

Place the finely chopped dark chocolate in a heatproof bowl.

Heat the cream in a small saucepan until it begins to steam. Do not allow it to boil vigorously.

Pour the hot cream over the chocolate and leave it untouched for two minutes.

Stir slowly from the centre outward until the ganache becomes smooth and glossy. Add the butter and stir until melted.

Allow the ganache to cool for approximately 10 minutes. It should remain pourable but should no longer feel hot.

9. Add the ganache topping

Pour the cooled ganache over the firm hazelnut mousse layer.

Tilt the tin gently or use a spatula to spread the ganache evenly across the surface.

Sprinkle the chopped toasted hazelnuts around the edge or over the entire cake. Add chocolate curls and a very small amount of flaky sea salt, when desired.

Return the cake to the refrigerator for at least two additional hours. Overnight chilling produces the cleanest slices.

10. Unmould and serve

Run a warm, thin knife carefully around the edge of the cake when acetate was not used.

Release the springform tin and transfer the cake to a serving plate.

For neat slices, dip a sharp knife into hot water, dry it and cut the cake. Clean and warm the knife between each slice.

Allow the cake to stand at room temperature for approximately 10 minutes before serving. This softens the mousse slightly and improves the flavour.

Helpful Tips

Use full-fat cream cheese for a stable filling. Reduced-fat versions contain more water and can produce a softer cake.

The hazelnut spread should be smooth and at room temperature so that it blends easily with the cream cheese.

For a stronger hazelnut flavour, add one teaspoon of hazelnut extract or two tablespoons of finely ground toasted hazelnuts to the filling.

The cake can be stored in the refrigerator for up to four days. Keep it covered to prevent the mousse from absorbing other flavours.

It may also be frozen for up to one month. Freeze it without the final hazelnut decoration, then thaw it overnight in the refrigerator.

Conclusion

This no-bake chocolate hazelnut mousse cake offers several contrasting textures in every slice: a crisp biscuit base, a light but creamy hazelnut filling and a smooth dark chocolate ganache.

Although the finished dessert looks elaborate, each layer is straightforward to prepare. Most of the work can be completed in advance, making it particularly convenient for celebrations and dinner parties. Serve it with fresh raspberries, whipped cream or a cup of strong coffee for a rich and polished dessert.