Preheat oven to 350 and grease a 8x8 baking dish.
In an electric mixer with whisk attachment, combine butter with 1 cup sugar, add cocoa, food coloring, 2 tsp vanilla extract, vinegar, salt, and eggs until combined.
Stir in flour and set aside 1/4 cup of mixture. Pour the remaining into the prepared dish.
In an electric mixer with whisk attachment, beat cream cheese until light and fluffy.
Add sugar, egg and vanilla approx. 5 minutes.
Spoon the cream cheese mixture in dollops and add the reserved batter in dollops as well onto the batter in the pan. Run a knife through the mixture to achieve the marbled effect.
Bake 30-35 minutes. Cool completely before cutting.