Remove the cream from 16 of the cookies and set aside in a bowl.
Melt the butter and mix it with the crushed cookies after removing the cream from them. You will obtain a dark and thick dough and spread it over a (preferably loose-bottomed) tin to form the base. Store in the refrigerator whilst preparing the rest.
Crush the sweets. The easiest way to do this is to use a powerful blender. If you do not have one, a mortar, pestle and patience will do.
Soak the sheets of gelatine in water for 5 minutes, then drain and dissolve in the 3 tablespoons of hot milk. Add the cream of the cookies and cream cheese to this mixture.
Beat the cream until it forms stiff peaks and add a few drops of green food colouring (add a little at a time until the desired colour is achieved).
Add the crushed sweets, then gradually add the cream cheese mixture with the food colouring.
Split the resulting dough into 2 parts and reserve a small amount for decoration.
Remove the tin containing the base from the refrigerator and add half the dough. Add a bed with the uncrushed cookies whose cream was not removed Finally, add the other part of the dough, smooth it down well and put it in the refrigerator for at least 6 hours.
PREPARE THE COATING: Melt the chocolate in a bain-marie or microwave oven (if you use a microwave, be careful with the cooking time). Mix with the cream and spread over the cake. With a pastry bag, use part of the mixture to make decorations on the chocolate coating.