• Preheat the oven to 180°C (350°F) and grease a 20cm round baking tin.
• Beat the butter, sugar and brown sugar together until light and fluffy.
• Beat in the eggs and vanilla extract.
• Lightly beat in the flour, cocoa, baking powder and baking soda.
• If you are adding the chocolate chips, add them now and stir them in.
• Split the cookie dough in half and press half into the base of the baking tin in an even layer. Ensure the dough comes up around an inch on the sides of the pan.

Cheesecake;

• Beat the cream cheese until smooth.
• Add the egg, vanilla and icing sugar and beat until all combined and smooth.
• Pour the cheesecake over the cookie base.
• Top with the remaining cookie dough and bake for 20 minutes.
• The middle will still wobble but the sides and top of teh cookie pie should be set.
• Allow it to come to room temperature and then place in the fridge for at least two hours.
• Leave it in the fridge longer for a more set cheesecake middle.