Crumble the cookies and mix them with nuts. If the nuts are also big, crumble them too. Melt chocolate and butter and mix it with the milk.
Pour the chocolate mass onto the cookies and nuts. Get a form for the cake and spread parchment paper on it. Pour the cake on it and make sure to press from the top and all sides. Put it in a fridge for the remainder of the night. You will be able to enjoy it the next day.