Preheat the oven to 350 degrees F. Line a square 8×8 baking pan with foil, leaving extra on the sides to lift the brownies out, then coat it with butter.

In a microwave safe bowl or cup, heat ½ cup of the butter until melted, allow to cool. Add the cooled butter to a large mixing bowl. Beat in the sugar, cocoa powder, food coloring, vinegar, vanilla extract, and salt, until well combined.

In a small bowl whisk the eggs. Add the eggs to the brownie mixture and stir until well combined. Gradually fold in the flour until just combined.

Reserve ¼ cup of the batter and pour the remaining batter into the prepared baking pan.

In a medium bowl beat together the cream cheese and sugar until fluffy. Add the egg and vanilla and beat until smooth.

Spread the cream cheese mixture on top of brownie batter in the pan. Spoon on the remaining brownie batter using a tablespoon, do not spread out. Using a knife, swirl the cream cheese layer into the brownie batter on top, creating a swirl pattern.

Bake for 25-30 minutes or until a toothpick comes out clean. Remove the pan from the oven and allow it to cool on a wire rack. Cut and serve. Store in airtight container in the refrigerator.