For the vanilla cheesecake filling, add cream cheese, sugar, heavy cream, egg, and vanilla to a bowl. Whisk on medium-low speed until a creamy mixture forms. Set aside.

For the chocolate cheesecake filling, add chocolate and heavy cream to a microwave-safe bowl. Microwave in 20-second increments until melted into a smooth ganache. Set aside.

Whisk cream cheese with sugar for the chocolate cheesecake filling until creamy. Fold in the ganache until combined. Set aside.

For the red velvet brownie batter, melt butter in a saucepan over medium heat until it has browned slightly. Remove from heat and stir in dark chocolate.

In a large bowl, whisk white sugar, brown sugar, eggs, and vanilla on high speed until pale and frothy (3-4 minutes).

Whisk in vinegar, red food color, and the butter/chocolate mixture until combined.

Sift in flour, cocoa powder, and salt. Gently fold until just combined. Optionally fold in chopped chocolate.

Preheat the oven to 350°F (conventional) and line a 9x9" baking pan with parchment paper.

Layer the brownie batter and cheesecake fillings as desired in the baking pan.

Bake for 30-35 minutes until a toothpick inserted in the middle comes out with moist, sticky crumbs attached.

Let the brownies rest in the pan for 20 minutes, then transfer to the fridge for 1 hour before slicing.