Preheat oven to 180 degrees C. Crush the biscuits and mix with the melted butter. Press into the bottom of a greased springform tin and bake 20 minutes. Let cool completely.
Melt the milk chocolate in a double boiler and add the cream and cocoa. Stir well and let cool slightly. With an electric mixer, beat the cream cheese. Add the icing sugar and melted chocolate. Beat until light and airy.
Pour over the biscuit base and chill overnight. If you like, decorate with icing sugar, fruit, nuts, etc.