01 - Preheat the 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 well combined. Add the egg, vanilla extract, and red food coloring, mixing until fully incorporated.
03 - Sift the flour, cocoa powder, and salt into the wet mixture. Fold gently until just combined—be careful not to overmix, which can make the brownies tough.
04 - In a small separate bowl, beat the softened cream cheese with sugar until smooth. Add the egg yolk and vanilla, continuing to mix until creamy and lump-free.
05 - Spoon approximately 1 tablespoon of brownie batter into each prepared muffin cup. Top each with about 1 teaspoon of the cream cheese mixture.
06 - Using a toothpick or small skewer, gently swirl the cream cheese mixture into the brownie batter in each cup. Make 2-3 circular motions to create a marbled pattern without over-mixing.
07 - Bake for 23-25 minutes, or until centers are set and a toothpick inserted comes out with a few moist crumbs. The tops should spring back lightly when touched.
08 - Let the brownie bites cool in the pan for 10 minutes before transferring to a wire rack. Cool completely before serving to allow the cream cheese swirl to set properly.