Preheat your oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment paper and grease it lightly. Gather all ingredients and ensure that the butter is melted and cooled slightly.

In a large mixing bowl, whisk together the all-purpose flour, cocoa powder, baking powder, and salt. Set aside for later use.

In another bowl, combine the granulated sugar and melted butter. Stir until well mixed. Add the eggs, one at a time, beating well after each addition. Mix in the vanilla and peppermint extracts.

Gradually add the dry ingredients to the wet mixture, stirring until just combined. Do not overmix. Fold in the chocolate chips until evenly distributed.

Pour the batter into the prepared pan, spreading it evenly. Bake in the preheated oven for 25 to 30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.

Remove the brownies from the oven and let them cool in the pan on a wire rack for at least 20 minutes. Once cooled, lift the brownies out of the pan using the parchment paper and cut into squares.

Store the brownies in an airtight container at room temperature for up to 5 days. For longer storage, individually wrap each brownie in plastic wrap and freeze for up to 3 months.