Decadent Chocolate Mousse Cake

Decadent Chocolate Mousse Cake

By Ann Reardon

This decadent chocolate cake has a crunchy cookie crumble, velvety smooth chocolate mousse, fluffy Italian meringue, and gooey salted caramel. All these different textures morph into mouthfuls of “mmms” and “ahhs.” It’s a guaranteed crowd-pleaser every time!

You can start making this dessert well ahead, leaving time on the day of your gathering to relax and enjoy yourself. I’d suggest making the crunchy cookie crumb, chocolate cake, and salted caramel on day one. Prepare the mousse and assemble on day two, leaving only the Italian meringue, decorating, and of course eating on day three.

Makes 8 – 10 slices


Crunchy Cookie Crumble

1 teaspoon cornstarch or corn flour

1 teaspoon salt

2/3 cup (105 g / 3.7 oz) plain or all-purpose flour

1/2 cup (105 g / 3.7 oz) sugar

2/3 cup (80 g / 2.8 oz) cocoa powder

6 tablespoons (80 g / 2.8 oz) melted butter

12.4 oz (350 g) milk chocolate to coat

Rich Chocolate Cake

10.6 oz (300 g) dark chocolate with 70 percent cocoa

2 cups (470 g / 17 oz) margarine or butter

12 large eggs (540 g / 19 oz)

3 ½ cups (730g / 25.8 oz) caster sugar or superfine sugar

2 cups (300 g / 10.6 oz) plain or all-purpose flour

6 tablespoons (45 g / 1.6 oz) cocoa powder

2 ½ teaspoons baking powder

Salted Caramel

1 ½ cups (325 g / 11.5 oz) sugar

¼ cup (60 mL / 2 fl oz) water

1 cup (350 g / 12.4 oz) glucose syrup or light corn syrup

1 cup (250 mL /8.5 fl oz) heavy cream (35 percent fat)

½ cup (125 mL / 4.2 fl oz) milk

Salt to taste

Chocolate Mousse

6 sheets gelatin or 1½ tablespoons powdered gelatin

Bowl of water if using gelatin sheets

1 ½ cups (375 mL / 12.7 fl oz) milk

3 tablespoons (60 g / 2.1 oz) glucose syrup or light corn syrup

6 large egg yolks (94 g / 3.3 oz)

22 oz (625 g) milk or dark chocolate

3 ½ cups (845 g / 29.8 oz) heavy cream (35 percent fat), whipped

Italian Meringue

1 ½ egg whites (45 g / 6 oz)

⅛ teaspoon cream of tartar

2 tablespoons water (32.5 mL /1.1 fl oz)


½ cup (125 mL / 4.23 fl oz) milk

4 chocolate bars

¾ cup (100 g / 3.5 oz) strawberries, washed

Edible flowers

8-inch (20 cm) cake ring

10-inch (25.5 cm) cake board

28 x 10 inch (70 x 25 cm) sheet of acetate


Crunchy Cookie Crumble

Preheat the oven to 180°C (350°F).

Put the cornstarch, salt, flour, sugar, and cocoa powder into a bowl and stir until combined. Add the melted butter and continue to mix it until it’s a crumbly dough.

Sprinkle chunks of cookie dough onto a baking sheet lined with baking paper and bake for 20 minutes. They will be quite soft when you first remove them from the oven but will crisp up as they cool. Once cold, tip half into an airtight container for later.

Break the milk chocolate into pieces and place in a bowl. Microwave on high for 1 minute, stir, then microwave 30 seconds, stir again, and repeat in 30-second bursts until it is completely melted. Pour half the crumbs into the bowl of melted chocolate and mix until they are coated. Spread out on a lined baking sheet and place in the refrigerator.

Rich Chocolate Cake

Preheat the oven to 180°C (350°F).

Place chocolate and margarine into a bowl and melt in the microwave on high for 1 minute. Stir the mixture, then microwave for another 30 seconds and stir again. Repeat in 30-second bursts, stirring in between each time, until melted. Mix in the sugar. Then add the eggs and whisk well. Sift the flour, cocoa powder, and baking powder together and mix into the cake mixture until just combined.

Pour into two 10 x 15 inch (25.5 x 38 cm) lined cake pans. Bake in the oven for 15–20 minutes or until a knife inserted into the center comes out clean. If your cake is looking done on top but is not yet cooked in the middle, place an empty baking sheet on the oven shelf just above it to protect the top from burning.

Cool on a wire rack.

Salted Caramel

Combine the water, sugar, and glucose syrup in a pan. Place over high heat and stir until the sugar is dissolved. Using a wet pastry brush, wash any sugar off the sides of the pan. Leave it to boil unstirred for 4–6 minutes or until it has a golden caramel color. Add the milk and cream, being careful of the burst of steam. At first the caramel will set because the liquid is cool, but continue stirring until the caramel melts completely.

Let the mixture boil unstirred until it reaches 107°C (224°F) on a candy thermometer—this will take about 2–3 minutes. Strain through a sieve into a heatproof bowl. Add in the salt, then stir through and leave the mixture to cool.

Chocolate Mousse

Put the sheets of gelatin into the bowl of cool water to soak. If using powdered gelatin, quickly mix with 3 tablespoons (45 mL/1.5 fl oz) of the milk and set aside.

Place the milk and glucose syrup in a large bowl and microwave on high until it bubbles. In a separate bowl, whisk the egg yolks with a little of the hot milk mixture to temper them. Add the rest of the hot milk mixture, whisking as you do so. Microwave for 5 seconds more. Squeeze the gelatin sheets to get rid of as much water as you can, then add them (or the softened powdered gelatin) into the milk mixture and stir until melted.

Pour this mixture over the chocolate and leave it for a couple of minutes until it melts. Stir well with a whisk until your mixture is smooth. Leave to cool to room temperature.

Fold in the whipped cream and use immediately or the mousse will set.

Italian Meringue

Shortly before assembly, make the Italian meringue.

Whisk the egg whites and cream of tartar until they form soft peaks.

Put the sugar and water in a saucepan and bring to a boil. Wash down the sides of the pan with a wet pastry brush, add a candy thermometer to the side of the pan, and leave unstirred until it reaches 114°C (238°F).

Immediately remove the sugar solution from the heat and, with the beaters running, pour in a thin stream into the egg whites. Continue to whisk on high speed until the outside of the bowl no longer feels hot. This usually takes about 5 minutes. You can speed up the cooling process by putting a bowl of iced water underneath the mixing bowl. It will be thick, smooth, and glossy when it is cool.


Level the cakes and cut two 8 inch (20 cm) circles from each cake. Reserve the cake offcuts as you will need them later.

Place a 20 cm (8 inch) cake ring onto a cake board and line with acetate. Beware: your mousse will seep out the bottom if your cake ring isn’t totally flat on the board. To keep this from happening, put about ¼ cup of mousse in the bottom, ensuring it is around all the edges, and place in the freezer for a few minutes so that it firms up quickly and seals any little gaps.

Place a layer of cake into the bottom of the cake ring, then sprinkle 2 tablespoons of milk over the cake layer. Add a handful of chocolate-coated cookie chunks. Drizzle on some divine salted caramel. Cover with 2½ cups or 625 mL (21 fl oz) of chocolate mousse.

Continue to layer it up in this manner all the way to the top. Refrigerate for at least 3 hours, preferably overnight.

Chop the chocolate bars into triangular chunks. If they contain caramel, you may need to put them in the freezer to make them easier to handle.

Remove the cake ring and peel off the acetate from the outside of the cake. Add caramel around the top edge, allowing some to drip down the sides of the cake.

On top of the cake, pile some cake offcuts across the center, then add crunchy cookie crumble on both sides.

Generously spoon Italian meringue across the middle so that it covers the cake offcuts. Toast the meringue using a blowtorch, then top with strawberries, edible flowers, and the chopped chocolate bars.

Video tutorial for this recipe can be found at Please visit Amazon or the Mango Publishing for more information about the cookbook.

Republished with permission from How to Cook That: Crazy Sweet Creations by Ann Reardon. Mango Publishing. 2021.

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