Crumble the biscuits in a metal container, add the powdered sugar, grated chocolate, starch and stir well. Pour in the milk and put the container on a low stove. Boil as you would a cream until slightly thickened, while stirring nonstop. Take the container off the stove and add the vanilla, leave the mixture to cool a bit.
Separate the whites from the yolks and beat the whites to foam. Beat the yolks with a fork and pour them in a thin trickle to the cooled cream mixture, stir. To them add the egg white foam and stir slowly until homogeneous from the top going down.
Pour the mixture into a greased and laid out with baking paper tray, bake in a preheated 356°F (180 °C) oven for about 30 min.
While still warm, take the cake out and pour the prepared glaze over it.
To make the glaze, melt the butter on low heat, add the pre-mixed together sugar, cocoa and milk.
Heat to boiling point while stirring nonstop to obtain a smooth, homogeneous mixture. Cut the cooled cream-cake into slices and serve.