Preheat your oven to 350°F (175°C). This ensures that your brownies bake evenly.
Line your 9x9-inch baking pan with parchment paper, allowing some overhang for easy removal later.
In a large mixing bowl, combine melted buttermilk, sugar, eggs, and vanilla extract. Whisk together until smooth.
Stir in red food coloring and white vinegar.
Sift together cocoa powder, flour, baking soda, and salt in a separate bowl. Gradually fold these dry ingredients into the wet mixture until just combined.
In another bowl, beat the softened cream cheese with sugar, egg, and vanilla extract until the mixture is smooth and creamy.
Spread half of the brownie batter into the prepared pan. Spoon the cheesecake mixture over the brownie layer, spreading it evenly. Drop spoonfuls of the remaining brownie batter on top and swirl.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. Allow to cool.
