For the base

1. Preheat the oven to 180°C. Line a baking tin with baking paper. Tip: grease the tin with margarine. Then cut a round the same size as the base and strips to cover the sides. Stick these into the tin.
2. Crumble the cookies in a food processor. Mix in the melted butter.
3. Tip the cookie crumbs out onto the bottom of the baking tin and press firmly with the back of a spoon.
4. Bake for 10 min. Allow to cool completely while you make the filling.

For the chocolate mousse layer

1. Melt the chocolate in the microwave on a low wattage setting and melt for bursts of 30 seconds at 600w, briefly stirring the chocolate between each interval). When all the chocolate is almost melted, keep stirring until the last bit also melts away. Set to one side.
2. In a small saucepan put the Zùsto and the eggs. Bring to a boil while continuing to stir with a whisk. When the mixture begins to thicken, remove the saucepan from the heat. Do not cook for too long because then you get fried eggs :). The mixture must stick to the back of your spoon.
3. Remove the saucepan from the heat and add the melted chocolate. Add the vanilla extract and set aside for a while (stirring occasionally).
4. Blend the margarine until soft for a few minutes. And little by little, pour in the chocolate batter (make sure it is no longer hot!).
5. In another mixing bowl, partly whip the cream. Add the 20g Zùsto and continue to beat the cream. Lightly scoop this under the chocolate batter and pour into the cake tin.
6. Place in the refrigerator for 6 h.