Preheat oven to 350° F. Line an 8 by 8-inch square baking pan with parchment paper and lightly grease with nonstick cooking spray. Set aside.
In a makeshift double boiler over low heat, melt chocolate and butter, stirring occasionally. Remove pan from the heat and whisk in the cocoa. Set aside to cool slightly.
In the bowl of a stand mixer, beat together eggs and sugar on medium-high speed for 1 minute. Reduce speed to low and add vanilla and salt until combined, about 15 seconds. Keep mixer on low and slowly pour in chocolate mixture into the egg mixture (you can also stir it in by hand).
Remove bowl from mixer and stir in the flour with a wooden spoon until just combined. Stir in the chopped Andes mints.
Pour batter in the prepared baking pan. Spread evenly. Bake the brownies for 25 to 30 minutes. Let the brownies cool completely in the pan, about 2 hours.
Ganache Topping
In a saucepan or the microwave, heat heavy cream until simmering. Place chocolate chips in a bowl, then pour heavy cream and mint extract over the chocolate. Let the mixture sit for 5 minutes, then stir until chocolate is melted. If the chocolate doesn’t melt, place the bowl in the microwave for 15 seconds on 50% power level.
Spread ganache over cooled brownies and sprinkle chopped Andes bits on top. Chill the brownies for 15 minutes before slicing and serving.
Notes
Good-quality chocolate makes a difference in the taste of the brownies and texture of the ganache. I prefer Ghirardelli or Guittard chocolate because they melt easily.Cocoa powder adds a deep cocoa flavor. Dutch process is preferred for a smooth flavor, but unsweetened cocoa can be used as well.Store in an airtight container at room temperature for up to 5 days.Freeze for up to 3 months. Wrap in plastic wrap and aluminum foil to prevent freezer burn.