For the brownies

1. Preheat the oven to 350°F. Generously grease an 8-inch baking pan, then line with parchment paper
2. Chop the chocolate into smaller pieces and melt the chocolate in a microwave-safe bowl in 30 second increments, stirring each time, and microwave until completely melted and smooth. Set aside to cool.
3. Combine the butter with the granulated sugar; beat together until well combined. Next, add the egg and egg yolk and beat for 60-90 seconds at a higher speed until the batter is fluffy (texture resembling a cake batter). Then add the vanilla extract and melted chocolate and beat until combined.
4. Combine the dry ingredients in a separate bowl and stir to combine. Add the dry ingredients to the batter and mix just until combined. Spread the batter evenly and bake at 350°F for 20-24 minutes. To test for doneness, rhe toothpick should still be somewhat gooey but not wet in the center. Remove from the oven and cool completely.

For the frosting

1. Soften the butter in the microwave for 15 seconds. Whip the butter for a couple of minutes using the paddle attachment, scraping down the bowl occasionally.
2. Add the powdered sugar, the mint extract, and the heavy cream. Continue beating at high speed until desired consistency is reached. Add green food coloring if desired. Spread over cooled brownies.

For the ganache

1. In a microwave-safe bowl, combine the chocolate with the heavy whipping cream. Melt the chocolate in the microwave in 30-second increments and stir until completely combined and melted. Allow to cool. Spread over the frosting and allow the ganache to set.