Preheat your oven to 350°F and prepare a baking sheet by lining it with parchment paper.
In a stand mixer fitted with the paddle attachment, add 1 cup of unsalted butter and both types of sugar: ¾ cup of brown sugar and ¾ cup of granulated sugar. Beat on high until the mixture is light and creamy, about 3 minutes.
Add in your 2 large eggs, 2 teaspoons of vanilla extract, and ½ teaspoon of mint extract. Mix until well combined.
In a separate bowl, sift together 1 ¾ cups of all-purpose flour, ¾ cup of unsweetened cocoa powder, 1 teaspoon of baking powder, and 1 teaspoon of salt.
Slowly add the dry ingredients to the wet ingredients in the mixer, mixing on low speed until just combined.
Gently fold in 1 cup of chopped Andes mints.
Scoop the dough in heaping tablespoon circles and place them on the baking sheet.
Bake for 8 to 10 minutes. Let the cookies cool on the pan for 5 minutes before transferring them to a cooling rack.
Once cool, whip ¾ cup of butter until light and fluffy, then add 3 teaspoons of mint extract, 1 teaspoon of vanilla, and 2 tablespoons of milk.
Gradually add 2 ½ to 3 cups of powdered sugar, mixing until you reach desired consistency.
Spread mint frosting onto cooled cookies.
Heat 1 cup of heavy whipping cream until simmering, then pour over 8 ounces of semisweet chocolate chips and stir until smooth.
Spread ganache over frosted cookies, and top with extra chopped Andes mints.
