Place chocolate chips in a small bowl and microwave on high for 30 seconds. Stir and microwave for another 30 seconds if needed until chocolate is smooth. Set aside.
In a medium bowl beat cream cheese, vanilla, sugar and egg. Combine with chocolate mixture.
Blend in milk and flour.
Add about ½ cup of cheesecake mixture to small bowl with melted chocolate. Set aside.
Spread remaining cheesecake mixture onto the brownie base to cover it completely.
Drop spoonfuls of the chocolate cheesecake mixture all over cheesecake layer in the pan.
Using a knife or skewer draw circles through the chocolate cheesecake mixture into the white cheesecake topping to create swirl pattern. Be careful not to touch the bottom brownie layer.
Bake in preheated oven 32-35 minutes, until the middle springs back when gently touched in the center. Cool then chill overnight before cutting.