Preheat oven to 175°C / 350°F. Grease and line an 8x8 inch pan with parchment paper.
Prepare Cream Cheese Layer: Whisk cream cheese, egg, cornstarch, vanilla, and sugar until smooth.
Prepare Brownie Layer: Brown butter in a saucepan over medium-low heat, stirring every 10 seconds. Once milk solids from butter sink and turn golden brown, transfer to heatproof bowl.
Add cocoa powder, oil, vanilla, and chopped chocolate; mix until dissolved.
Add vinegar and food color. Mix and let the mixture cool at room temperature for 15-20 minutes.
Whisk eggs and light brown sugar (for 4-6 minutes) until dissolved and mixture turns into a light pale color.
Add powdered sugar; mix until combined (1-2 minutes).
Combine egg mixture with browned butter mixture; mix until combined.
Add flour and chocolate chips. Mix until just combined; avoid overmixing.
Transfer half of the brownie mixture to the prepared pan. Reserve 30g / 2-3 tbsp of the cream cheese mixture; add the remaining mixture on top of the brownie layer.
Top with the remaining brownie batter; add the reserved cream cheese mixture. Make swirls.
Bake for 35-40 minutes or until the edges are golden and the center is slightly fudgy.
Let cool completely before cutting.
