Preheat your oven to 350°F (175°C). Grease the baking pan lightly or line it with parchment paper for easy removal.
Melt the unsalted butter in a large mixing bowl. Allow it to cool slightly.
Add the granulated sugar to the melted butter and mix until well combined.
Add the eggs one at a time, mixing thoroughly after each addition. Incorporate the vanilla and peppermint extracts.
In another bowl, whisk together the all-purpose flour, cocoa powder, salt, and baking powder.
Gradually add the dry ingredients to the wet mixture, stirring until just combined. If desired, fold in the chocolate chips.
Pour the brownie batter into the prepared baking pan and spread evenly.
Bake in the preheated oven for 25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Remove from the oven and immediately sprinkle the crushed peppermint candy over the top, pressing lightly to adhere.
Allow the brownies to cool completely in the pan before cutting them into squares.