01 - Preheat the oven to 350°F. Line an 8x8 inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - Whisk together melted butter and sugar until smooth. Add eggs, vanilla extract, and red food coloring; whisk until fully combined.
03 - Sift in the flour, cocoa powder, and salt. Fold gently with a spatula until just combined; do not overmix.
04 - Reserve 1/4 cup of the red velvet batter and set aside. Pour the remaining batter into the prepared pan and spread evenly.
05 - Beat the cream cheese with sugar until smooth. Add egg and vanilla extract; mix until creamy.
06 - Pour the cheesecake mixture over the brownie batter in the pan. Smooth evenly.
07 - Drop spoonfuls of the reserved red velvet batter on top of the cheesecake layer. Use a knife or skewer to gently swirl the batters together for a marbled effect.
08 - Bake for 33-36 minutes, or until the center is just set and a toothpick inserted in the center comes out with a few moist crumbs.
09 - Cool completely in the pan on a wire rack before lifting out and cutting into squares.