Preheat your oven to 325°F (165°C) and line an 8-inch square baking pan with parchment paper.

Melt ½ cup of salted butter until glossy and warm, then mix with light brown sugar until smooth. Add eggs one at a time, then stir in peppermint extract.

In a separate bowl, whisk together flour, cocoa powder, espresso powder, cornstarch, and baking powder. Gently fold dry ingredients into the wet mixture until just combined.

Fold in chocolate chips, reserving some for topping. Transfer the batter into the prepared pan and smooth the top.

Bake for 28-30 minutes. Check for doneness by inserting a toothpick; it should come out with a few moist crumbs.

Allow the brownies to cool completely in the pan on a wire rack for 30-45 minutes.

Whisk together melted butter, cocoa powder, and powdered sugar. Gradually add milk until reaching a smooth consistency.

Spread the frosting evenly over the cooled brownies.

Sprinkle crushed peppermint candy over the frosted brownies for decoration.

Slice with a hot knife into squares and enjoy!