Place the biscuits in a food processor and pulse until ground.
Add the cocoa and sugar and mix well then pour in the melted butter and give it a quick pulse to mix well.
Transfer the mixture into a round cake pan (22-24cm diameter), lined with parchment paper. Set aside.
Filling:
For the filling, mix all the ingredients together in a bowl. Using sour cream is not compulsory, but I love its slightly tangy flavor in cheesecakes and every other cake for that matter. You can replace it with heavy cream or cream cheese or even yogurt.
Pour the filling over the crust and bake the cheesecake at 330F for 50 minutes. It has to set, but not rise. When done, the center of the cheesecake looks set if you shake the pan slightly. Remove from the oven and let it cool down.
Glaze:
Bring the heavy cream to the boiling point.
Remove from heat and stir in the chocolate.
Mix well until melted and smooth.
Pour the glaze over the cheesecake and refrigerate 1 hour before serving.