Line a 40 x 25.5 cm pan with parchment paper and preheat the oven to 180°C. This ensures the cake doesn’t stick and bakes evenly.

Combine 45g hot water and 25g cocoa powder until smooth, and set aside. This step builds the chocolatey base flavor.

Whisk 3 egg whites with a pinch of salt, gradually adding 60g sugar in three batches. Stop when soft peaks form for the right consistency.

Beat 3 egg yolks with 20g sugar until dissolved, then mix in the cocoa mixture. This creates a smooth, rich batter base.

Fold in the whipped egg whites, sift in 50g cake flour, and mix gently. Add 20g vegetable oil to keep the batter moist and smooth.

Pour the cake batter into the pan, smooth it out, and bake at 180°C for 15-17 minutes. Cool completely before moving to the next step.

Heat 100g milk with 2 egg yolks, 30g sugar, and 1 tsp instant coffee, then stir in 3 gelatin sheets. Combine with 70g melted dark chocolate and fold into whipped cream.

Cut the sponge into two layers, place one in a mold, and layer with half the mousse. Add the second layer, then spread the rest of the mousse on top, smoothing it out.

Chill the cake for 4 hours, then pour a glaze made of cocoa, water, cream, sugar, and gelatin over it. Let it set in the fridge for 1-2 hours for a glossy finish.

Decorate with melted white chocolate and strawberries, then slice and enjoy the soft, rich chocolate mousse cake!