Preheat oven to 350 degrees. Prepare an 8x8 or 9x9 baking dish with cooking spray and use parchment paper to help remove brownies after cooking.
In a large microwave safe bowl melt 1/2 cup unsalted butter and the chocolate chips until smooth. (20 second increments).
Stir in 1 cup of sugar, 2 tsp vanilla, 1/4 cup cocoa powder, 1/8 tsp salt, and 1-2 TBS red food gel and 3/4 tsp white vinegar.
Whisk in the eggs one at a time. Fold in the flour until incorporated. Don't over mix.
Pour brownie mix into prepared pan. (Reserve 3-4 TBS).
To make the cheesecake swirl, use a hand held electric mixer on medium speed to beat the cream cheese, sugar, egg yolk, and vanilla in a medium bowl until smooth (1 minute).
Dollop spoonfulls of cream cheese mixture on top of brownie batter. Cover the cream cheese with the reserved brownie mix. Swirl a knife through the layers.
Bake for 28-30 minutes until a toothpick comes out clean. Allow to cool completely before cutting.
