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.
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 the brownie batter. Spread the remaining batter evenly into the prepared pan.
05 - Beat softened cream cheese until smooth. Incorporate sugar, egg yolk, and vanilla extract, mixing until creamy and well-blended.
06 - Drop spoonfuls of cheesecake mixture over the brownie base. Add dollops of the reserved red velvet batter on top. Gently swirl with a skewer or knife to create marbled patterns.
07 - Bake for 33–36 minutes until the center is just set and a toothpick inserted comes out with moist crumbs.
08 - Cool completely in the pan before lifting out using the parchment overhang. Slice into 16 equal squares.