• Preheat oven to 350°F (177°C). Line a 9x13-inch baking pan with parchment paper, leaving an overhang on the sides for easy removal. Lightly spray the parchment with nonstick cooking spray.

Brownie Layer

• In a large bowl, whisk together the melted butter and granulated sugar until combined.
• Add the eggs and vanilla extract. Mix until smooth.
• Add the flour, cocoa powder, salt, and baking powder. Stir gently until just combined. Do not overmix.
• Spread the batter evenly into the prepared pan.
• Bake for 25 to 30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs, but no wet batter.
• Let the brownies cool completely in the pan on a wire rack, about 1 hour.

Peppermint Filling

• In a medium bowl, beat the confectioners’ sugar, softened butter, peppermint extract, food coloring, and 2 tablespoons of milk with an electric mixer until smooth and spreadable. If needed, add an extra tablespoon of milk for a softer, creamy consistency.
• Spread the filling evenly over the cooled brownies using an offset spatula.
• Refrigerate for 15 to 30 minutes, or until the mint layer is firm.

Chocolate Ganache

• Place the chocolate chips and butter in a microwave-safe bowl.
• Microwave in 20 to 30 second intervals, stirring after each, until the mixture is glossy and mostly melted.
• Stir until completely smooth. If needed, microwave for an additional 10 seconds. Watch closely so the chocolate does not overheat.
• Let the ganache cool slightly, about 5 to 10 minutes.
• Pour over the chilled mint layer and spread into an even layer.

Chill, Slice, & Serve

• Refrigerate chocolate mint brownies for at least 1 to 2 hours, or until the ganache is fully set. For the cleanest slices, chill longer or overnight.
• Use the parchment overhang to lift the brownies out of the pan.
• For neat squares, run a sharp knife under hot water, wipe dry, and press straight down to cut. Clean and rewarm the knife between slices.