01 - Preheat the oven to 350°F. Line an 8x8 inch baking pan with parchment paper, allowing some overhang for easy removal.
02 - In a large bowl, whisk together the melted butter and granulated sugar until smooth and well combined. Add the eggs, vanilla extract, and mint extract, whisking until fully incorporated.
03 - Sift the cocoa powder, flour, and salt directly into the wet mixture. Gently fold together until just combined, being careful not to overmix.
04 - Fold in the semisweet chocolate chips until evenly distributed throughout the batter.
05 - Pour the batter into the prepared pan, spreading evenly. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
06 - Place the chopped dark chocolate and butter in a heatproof bowl. Heat the heavy cream in a small saucepan until just simmering, then pour over the chocolate mixture. Let stand for 1 minute, then stir until completely smooth and glossy.
07 - Allow the brownies to cool completely in the pan on a wire rack. Pour the prepared ganache over the cooled brownies, spreading evenly with a spatula.
08 - Refrigerate for 20-30 minutes until the ganache is set. Slice into 16 squares and serve.