Preheat your oven to 350°F (175°C) and grease an 8×8-inch baking dish.

Melt the butter and cocoa powder together in a medium saucepan over low heat until smooth.

Stir in granulated sugar until well combined, then let it cool slightly before adding eggs one at a time, mixing well after each addition.

In a separate bowl, whisk together flour and mint extract, then fold into the chocolate mixture until just combined.

Pour batter into the prepared baking dish and bake for 20-25 minutes or until a toothpick comes out clean or with few moist crumbs.

Allow brownies to cool completely before cutting into squares; top with green sprinkles if desired.