Beat together the cream cheese, sugar and vanilla extract until smooth and combined. Place 9 - 12 teaspoons of the mixture on a baking tray lined with parchment paper. Freeze until solid - about 1 - 2 hours.

Preheat the oven to 180C/350F/Gas 4, and line a baking tray with parchment paper, or a silicone mat. Set aside.

Whisk together the flour, cornflour, baking soda, salt, and cocoa powder. Set aside.

Whisk together the butter and sugars until combined. Add the egg, and vanilla, and mix until combined. Add the dry ingredients, and mix until just combined.

Roll the dough into 2oz balls - about 9 big balls. You could also make about 12 smaller balls. Form the balls into flat, round circles, and place 1 teaspoon of the cheesecake mixture into the centres.

Form the dough back into balls, sealing the cheesecake centre. Roll each ball in granulated sugar, and press some chocolate chips on top.

Place the dough balls on the prepared baking tray, flatten them slightly (them won't spread much in the oven) and bake for 10 - 12 minutes. Allow to cool on the baking tray for 5 minutes before transferring to a wire rack to cool completely.