Preheat your oven to 350°F (175°C). Grease and line a 9x13 inch baking pan with parchment paper, leaving an overhang for easy removal.
In a mixing bowl, combine the melted butter and granulated sugar. Mix until well combined.
Add the eggs one at a time, mixing well after each addition. Then, stir in the vanilla extract and peppermint extract.
In a separate bowl, whisk together the flour, cocoa powder, salt, and baking powder.
Gradually add the dry mixture to the wet ingredients, mixing until just combined. Be careful not to overmix.
Fold in the chocolate chips until evenly distributed in the batter.
Pour the brownie batter into the prepared baking pan, spreading it evenly.
Bake in the preheated oven for 25 minutes or until a toothpick inserted in the center comes out with a few moist crumbs (not wet batter).
Allow the brownies to cool in the pan for about 10 minutes before lifting them out using the parchment paper.
Once completely cooled, top with crushed peppermint candies. Cut into 12 squares and serve.