Light Triple Chocolate Mousse Cake

📝 Ingredients

• 70 g rolled oats
• 15 g unsweetened cocoa powder (10 g for the base, 5 g for decoration)
• 20 g unsalted butter, melted + 20 g honey (for the base)
• 100 g dark chocolate 70%
• 80 g milk chocolate
• 60 g white chocolate
• 4 eggs, whites and yolks separated (2 yolks and 2 whites for the dark layer, 1 white for the milk layer, 2 yolks and 1 white for the white layer)
• 300 g plain 0% skyr (150 g for the milk layer, 150 g for the white layer)
• 180 ml semi-skimmed milk (50 ml for the dark layer, 30 ml for the milk layer, 100 ml for the white layer)
• 25 g caster sugar (10 g for the dark layer, 5 g for the milk layer, 10 g for the white layer)
• 4 gelatine leaves of 2 g (2 for the milk layer, 2 for the white layer)
• 1 tsp vanilla extract

🍴 Utensils

• 20 cm cake ring
• Electric hand mixer
• Silicone spatula
• Saucepan and bowl for a bain-marie
• Mixing bowls
• Small sieve

📖 Steps

1. Preheat the oven to 180 °C. Mix the oats, 10 g cocoa, the melted butter and the honey, then press the mixture firmly into the bottom of the ring, set on a baking tray lined with baking paper. Bake for 12 min, until the base smells like toasted biscuits, and leave to cool.
2. Slide the base, still in its ring, onto the serving plate with its paper, then line the inside of the ring with a 6 cm high strip of baking paper. Take the skyr out of the fridge 30 min beforehand: if it's too cold, it makes the gelatine set in lumps.
3. Dark layer: melt the dark chocolate with 50 ml milk in a bain-marie, smoothing with a spatula. Off the heat, leave to cool slightly for 2 min, then beat in 2 yolks one at a time. Whisk 2 whites to stiff peaks, add 10 g sugar and whisk for another 30 s, until glossy.
4. Briskly mix a third of the whites into the chocolate to loosen it, then fold in the rest with a silicone spatula, lifting the mixture from the bottom upwards, without knocking out the air bubbles. Pour over the base, smooth the top and place in the freezer for 20 min so the surface sets.
5. Milk layer: soak 2 gelatine leaves in cold water for 5 min. Melt the milk chocolate with 30 ml milk in a bain-marie, then, off the heat, dissolve the well-squeezed gelatine in it. Leave to cool slightly for 5 min, then whisk in 150 g skyr until you have a smooth cream.
6. Whisk 1 egg white to stiff peaks with 5 g sugar and gently fold it into the milk chocolate cream. Pour it slowly over the back of a spoon onto the dark layer so as not to make a dent in it, smooth the top and return to the freezer for 20 min.
7. White layer: soak 2 gelatine leaves. Whisk 2 yolks with 5 g sugar, pour in 100 ml hot milk and cook over low heat, stirring, for 3 to 4 min without boiling, until the custard coats the spatula. Off the heat, melt the squeezed gelatine, the white chocolate and the vanilla into it.
8. Leave the cream to cool slightly for 10 min, whisk it with 150 g skyr, then fold in the last egg white, whisked to stiff peaks with 5 g sugar. Pour over the milk layer, smooth the top and refrigerate for at least 6 h, ideally overnight.
9. Remove the ring, then peel off the strip of paper. Dust with 5 g cocoa through a small sieve and cut into 8 slices with a knife dipped in hot water and wiped between each slice, for nice clean layers.