For the brownie:
For the cheesecake:
1. Preheat oven to 350F (180C). line a 8-inch (20cm) square baking pan with parchment paper. Set aside.
2. Place chopped chocolate and butter in a large heat proof bowl. Set the bowl over a double boiler and melt completely. Add both sugars and stir. Allow to cool slightly.
3. In a separate bowl sift flour, cocoa powder, baking powder and salt.
4. To the chocolate mixture add eggs, one at the time and whisk until combined.
5. Add flour mixture to the chocolate mixture and stir until combined.
6. Pour the batter into prepared pan and spread evenly. Reserve 1/2 cup for later.
7. In a bowl whisk cream cheese, sugar, egg and vanilla extract.
8. Pour cream cheese mixture over the brownie layer. Take your reserved ½ cup brownie batter and drop over cheesecake. Use a knife to gently swirl the filling, creating a marbled effect.
9. Bake for 25-30 minutes, until center is set and a toothpick inserted in the center comes out mostly clean with a few fudgy crumbs.
10. Let cool completely, cut into squares and serve.