1. For easy removal of the cake, place a round circle of parchment paper on bottom of a 9 inch springform pan, alternatively spread melted butter on bottom of the pan and set aside.
2. In a bowl placed over low simmering water, stir butter and chocolate chips until melted.
3. Add cocoa powder and whisk smooth. Add egg and vanilla extract and whisk until well combined.
4. Add flour, baking powder and dash of salt and stir until smooth. Pour batter into pan and place in the oven.
5. Bake at 350°F for 8-10 minutes or until center of brownie layer feels set when lightly pressed with a finger.

Cheesecake layer:

1. Arrange cookies in a single layer onto the baked brownie layer.
2. Chop milk chocolate in small pieces and place in a bowl.
3. Bring 1 cup of heavy cream to a boil, remove from heat and pour onto milk chocolate, whisk smooth.
4. Place white chocolate chips in a separate bowl. Bring remaining heavy cream to a boil and pour onto white chocolate chips, whisk smooth.
5.  On low speed blend one package of cream cheese with 1/4 cup of sugar, mix on low speed until no lumps remain. Add 1 tablespoon vanilla and milk chocolate mixture. Pour onto cookie-brownie layer and set aside.
6. Clean bowl and on low speed mix remaining cream cheese package with 1/4 cup sugar on low speed until no lumps remain. Add 1 tablespoon of vanilla extract and white chocolate mixture. Roughly chop 10 cookies and mix into batter.
7. Pour mixture into pan covering milk chocolate-cheese layer.
8. Place into freezer for 4-8 hours or overnight.
9. Remove from freezer 20 minutes before serving.
10. If desired garnish with berries, caramel or chocolate sauce.