Preheat the oven to 350 F. Line 9 x 9 inch baking pan with parchment paper or spray with nonstick spray.

TO MAKE THE BROWNIE – In a medium dish combine flour, cocoa and salt. Set aside. In a large dish combine melted butter and sugar. Add vanilla, vinegar and eggs and beat until combined. Slowly fold in dry ingredients and beat at low speed until well combined. Pour ¼ of the batter in a separate, smaller dish. Put red color in a larger dish and beat until combined. Put green or blue color in a smaller one and beat until combined.

TO MAKE CHEESECAKE FILLING. In a medium dish beat cream cheese and sugar at medium speed. Add vanilla and egg white and beat until creamy. Finally add flour and beat to combine. Pour red brownie batter in the baking pan and spread evenly. Gently spread cheesecake mixture over red velvet brownie layer. Drop spoonfuls of the green velvet brownie batter on top of the cheesecake. Drag a toothpick or a knife over the batter and cream cheese mixture to create swirls. Bake for 25-30 minutes or until a toothpick placed in the center comes out clean. Take out of the oven and leave to cool at a room temperature, and then transfer to fridge to cool completely.