01 - Set the oven to 350°F and line an 8-inch square baking pan with parchment paper, allowing excess paper to overhang for easy removal.
02 - Whisk together melted butter and granulated sugar in a large bowl until uniform.
03 - Add eggs and vanilla extract to the butter mixture and beat until smooth and homogenous.
04 - Sift cocoa powder, all-purpose flour, salt, and baking powder into the wet mixture. Gently fold until just combined to avoid overmixing.
05 - Transfer the batter evenly into the prepared pan, smoothing the surface.
06 - In a medium bowl, beat cream cheese until smooth. Add sugar, egg yolk, peppermint extract, and optional food coloring, mixing to a creamy consistency.
07 - Spoon dollops of the cream cheese mixture over the brownie batter. Use a knife or skewer to swirl the cream cheese gently into the batter, creating a marbled effect.
08 - Sprinkle crushed peppermint candies on the surface if desired for added texture and flavor.
09 - Place pan in the oven and bake for 35 minutes or until the center is set and a toothpick inserted comes out with a few moist crumbs.
10 - Allow brownies to cool completely in the pan. Remove using parchment paper overhang and cut into 16 squares before serving.