Wrap the bottom and sides of a cake form with removable ring with clear plastic wrap. Mix together the milk and 3 1/3 tbsp (50 g) of the sugar.
Dip the biscuits in the milk and arrange them in the form.
Smear a thin layer of it over the biscuits. Arrange a 2nd layer of biscuits, smear with chocolate again. Repeat in this order, be sure to finish off with biscuits.
Leave it to harden for 20 min. in the freezer.
Take it out and cover with a platter.
Smear the entire cake with the remaining chocolate cream to hide the gaps in the bottom and sides.