Preheat your oven to 350°F (176°C) so it’s ready when your batter is done. Line a 9×9 inch baking pan with parchment paper and lightly grease the sides. This helps the brownies come out cleanly without sticking.
In a mixing bowl, combine melted butter and sugar and whisk until the mixture looks smooth and slightly glossy. Then add eggs, vanilla extract, white vinegar, and red food coloring, and whisk again until everything is fully blended and evenly colored.
In a separate bowl, mix together the flour, cocoa powder, and salt. Slowly add the dry ingredients into the wet mixture and stir gently until just combined. Try not to overmix so the brownies stay soft and fudgy.
In another bowl, beat the cream cheese and sugar until completely smooth and creamy. Add the egg white and vanilla extract, then mix again until the cheesecake batter is silky with no lumps.
Spread about three-quarters of the brownie batter into your prepared pan and smooth it out evenly so it reaches all corners.
Spoon the cheesecake mixture over the brownie layer in small dollops. Take a toothpick or skewer and gently swirl it into the batter to create a marbled effect. Don’t over-swirl — you want visible layers.
Add the remaining brownie batter on top in small spoonfuls, then lightly swirl again to create a beautiful red velvet cheesecake pattern.
Bake for 25–30 minutes, or until the edges are set and the center still looks slightly soft. Avoid overbaking to keep the brownies fudgy.
Let the brownies cool completely at room temperature, then place them in the fridge for at least a while to help the cheesecake layer set properly.
Once chilled, slice into neat bars and serve. The texture will be rich, creamy, and perfectly fudgy in every bite.