Prepare the Pan

• Preheat your oven to around 175 °C (350°F).

• Line a square or rectangular baking pan with parchment paper, leaving an overhang for easy removal later.

Make the Brownie Batter

• In a bowl, whisk together the melted butter and sugar until smooth.

• Add the eggs and vanilla, mixing until well combined.

• Stir in the cocoa powder, flour, and salt until just combined.

• Mix in red food coloring (and optional vinegar) until the batter has a vibrant red hue.

Prepare the Cheesecake Mixture

• In another bowl, beat together the cream cheese and sugar until smooth.

• Add the egg (and optional vanilla) and mix until fully incorporated.

• (If making a two-tone swirl, mix a small portion of this mixture with cocoa powder + red coloring.)

Layer & Swirl

• Pour half of the red velvet batter into the prepared pan.

• Dollop the plain (and colored, if using) cheesecake mixture on top in spoonfuls.

• Add the remaining brownie batter, then use a knife or skewer to swirl the layers gently, creating a marbled effect.

Bake

• Bake for about 35–45 minutes, or until the top is set and a toothpick inserted into the center comes out with moist crumbs (not wet batter).

• Be careful not to overbake — you want a little jiggle in the center for fudginess.

Cool & Chill

• Let the brownies cool in the pan for at least 20–30 minutes, then transfer to the fridge for 2–4 hours (or overnight) to firm up and develop flavor.

Serve

• Use the parchment overhang to lift the brownies out of the pan.

• Cut into squares and serve chilled or at room temperature.