Brownies:

2 large eggs

1/2 cup unsalted butter

1 cup granulated sugar

2 teaspoons vanilla extract

1/4 cup unsweetened cocoa powder

1/8 teaspoon salt

1 Tablespoon liquid red food coloring

3/4 teaspoon white vinegar

3/4 cup all-purpose flour

Cheesecake Swirl:

8 ounces cream cheese, softened

1/4 cup granulated sugar

1 egg yolk

1/2 teaspoon vanilla extract

Preheat the oven to 350°. Spray 8×8 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 in 30 second increments until melted. Stir in 1 cup sugar, 2 teaspoons vanilla extract, cocoa powder, salt, food coloring, and vinegar.  Whisk in the eggs, then fold in the flour until completely incorporated. Do not overmix. Pour the brownie batter into prepared baking pan, leaving about 3-4 Tablespoons for the top. Make the cheesecake swirl. With a hand-held mixer on medium speed, beat the softened cream cheese, 1/4 cup sugar, egg yolk, and 1/2 teaspoon vanilla in a medium bowl until completely smooth – about 1 minute. Dollop spoonfuls of the cream cheese mixture on top of the prepared brownie batter. Cover with the last few Tablespoons of brownie batter. Glide a knife through the layers, creating a swirl pattern.  Bake the brownies for 28-30 minutes or until a toothpick inserted in the middle comes out clean. Allow the brownies to cool completely before cutting into squares.