Preheat the oven to 350°F. Spray baking pan with nonstick spray. Set aside. Make the brownie layer first:
In a small bowl, beat the 2 eggs together. Set aside.
Melt the butter in a large microwave safe bowl until melted completely. Add melted butter to mixer.
Mix on low and add each ingredient individually ensuring each is mixed before adding the next: 1 cup of sugar, 2 teaspoons vanilla extract, cocoa powder, salt, food coloring, and vinegar.
Whisk in the eggs you beat and set aside earlier.
Fold in the flour until completely incorporated.
Place the brownie batter into prepared baking pan (sprayed first with baking spray) leave a few Tablespoons for the "swirl".