01 - Preheat oven to 350°F. Line an 8-inch square baking pan with parchment paper, allowing overhang for easy removal.
02 - Whisk melted butter and granulated sugar in a large bowl until smooth. Add eggs, vanilla extract, and red food coloring, mixing thoroughly to combine.
03 - Sift cocoa powder, flour, and salt into the wet mixture. Fold gently until just combined—avoid overmixing to maintain fudgy texture.
04 - Reserve 1/4 cup of brownie batter for later use. Spread remaining batter evenly in the prepared pan, smoothing the surface with a spatula.
05 - Beat softened cream cheese until smooth and creamy. Add sugar, egg yolk, and vanilla extract, mixing until fully incorporated and lump-free.
06 - Drop spoonfuls of cheesecake mixture evenly over the brownie base. Add small dollops of reserved red velvet batter across the cheesecake layer.
07 - Drag a skewer or knife through the batters in a figure-eight or swirling motion to create a marbled pattern. Avoid over-swirling to maintain distinct layers.
08 - Bake for 33-36 minutes until the center appears set and a toothpick inserted comes out with moist crumbs. The edges should be slightly firm but the center remains slightly soft.
09 - Allow brownies to cool completely in the pan. Use parchment overhang to lift out, then cut into 16 equal squares with a sharp knife.