Melt the butter gently.
Place the biscuits into a food processor and crush thoroughly, add the melted butter through the spout and mix well.
Tip the biscuit base into a springform tin and press down well and evenly with the back of a spoon. Chill while making the filling.
Whip the cream until soft peaks form and set aside.
Melt the chocolate in a double boiler. The water should not boil and the base of the bowl should not touch the water.
Place the cream cheese and sugar into the food processor and blend well.
Pour the melted chocolate into the spout while blending. Add the cocoa and remove to a large bowl.
Make sure the mixture is cool and fold in the cream. Place this cheesecake mix on to the biscuit base and chill for 24 hours before serving.