01 - Preheat the oven to 350°F. Line an 8x8 inch baking pan with parchment paper, allowing overhang for easy removal.
02 - Whisk melted butter and sugar in a large bowl until smooth. Add eggs, vanilla extract, and red food coloring; whisk until fully combined.
03 - Sift flour, cocoa powder, and salt into the batter. Fold gently with a spatula until just combined; avoid overmixing.
04 - Reserve 1/4 cup of the red velvet batter. Pour remaining batter into the prepared pan, spreading evenly.
05 - Beat cream cheese with sugar until smooth. Add egg and vanilla extract; mix until creamy and well incorporated.
06 - Pour cheesecake mixture over the brownie batter in the pan, spreading evenly to cover the base.
07 - Drop spoonfuls of reserved red velvet batter onto cheesecake layer. Use a knife or skewer to swirl gently for a marbled effect.
08 - Bake for 33-36 minutes until center is just set. A toothpick inserted should come out with moist crumbs.
09 - Cool completely in pan on wire rack before lifting out. Cut into squares for serving.