01 - Preheat oven to 350°F. Line a 24-cup mini muffin tin with paper liners or lightly grease each cup with cooking spray.
02 - In a medium bowl, whisk together melted butter and sugar until smooth and glossy. Beat in egg, vanilla extract, and red food coloring until fully combined and uniform in color.
03 - Sift flour, cocoa powder, and salt directly into the wet mixture. Gently fold with a spatula until just combined—stop immediately when no dry streaks remain to prevent tough brownies.
04 - In a separate bowl, beat softened cream cheese with a hand mixer until completely smooth. Add sugar, egg yolk, and vanilla extract; continue mixing until creamy and no lumps remain.
05 - Spoon approximately 1 tablespoon of red velvet batter into each prepared muffin cup, filling about halfway. Top each with 1 teaspoon of cheesecake mixture. Use a toothpick or skewer to swirl gently for a marbled effect.
06 - Bake for 22 to 25 minutes until centers are just set and edges pull slightly away from the sides. The tops should feel firm but spring back lightly when touched.
07 - Let cool in the pan for 10 minutes to set structure. Carefully transfer bites to a wire rack and cool completely before serving or storing.