Crumble the biscuits in a bowl, add the melted butter to them. Stir well, to obtain a homogeneous mixture.
Lay out a 10″ (25 cm) form with baking paper. Pour the mixture into it and press firmly to the bottom to form an even layer.
Pour the milk in a pot on the stove and warm it up. In a bowl, beat the egg yolks, sugar and starch. Add the warm milk to the yolk mixture, while stirring energetically. Return to the stove and stir until it begins to thicken. Add the melted chocolate and stir well.
Pour the cream over the biscuits.
In a clean bowl, beat the egg whites. Add the sugar and continue beating to stiff tips. Add the essence and distribute the mixture over the cream.
Heat the oven to 347°F (175 °C) and bake the cake 25-30 min. Take it out of the oven, leave to cool a bit and serve.