Grease and line a loose based 20cm tin
Melt the butter and mix in with the biscuits crumbs. Pour onto the base of the tin and press down with the back of a wooden spoon until well compressed
Mix together the cream, cheese and sugar until a smooth consistency and then stir in the raspberries.
Melt the chocolate, either in the microwave or in a bowl over a pan of boiling water.
Quickly swirl in the melted chocolate to the cheesecake mix the then poor on top of the biscuits. Smooth with a pallet knife of the back of a spoon and then leave to chill in the fridge for 2 hours before serving.
Meanwhile make the coulis by heating the blackberries with the sugar and water until the berries are soft.
Whiz the mixture in a blender and then strain through a sieve so smooth and glossy.
Set aside until ready to serve
To make the chocolate sauce heat all the ingredients on a low heat until the chocolate has melted and the sauce is smooth and glossy. This can be made ready to serve or in advance and then re-heated for 1 minute in the microwave.