Preheat oven to 350°F and prepare cupcake tin with liners.
Add a cookie to the bottom of each of the 16 cupcake liners.
Place the remaining cookies into a bag and crush them into pea-sized crumbs. Set aside.
Add flour, sugar, cocoa powder, salt, baking powder and baking soda to your mixing bowl (I use a stand mixer with the whisk attachment). Stir until combined.
In a separate bowl, whisk together the oil, buttermilk, egg and vanilla. Once combined, add in the coffee slowly so you don't cook the eggs.
Pour the wet ingredients into the dry ingredients and stir slowly until combined. Then mix on high for two minutes, scraping the sides halfway through. Stir in the cookie crumbs.
Fill cupcake liners about ⅔ full and bake for 14-17 minutes or until a toothpick comes out clean. (A few crumbs sticking to the toothpick is fine, but you don't want it gooey).
Cool in the pan for a few minutes then remove to a wire cooling rack to cool completely.
In a stand mixer with the paddle attachment, beat the softened butter for a minute or until light and fluffy. Add powdered sugar, milk, extract and coloring. Beat on high for 2 minutes. If the frosting is too thin, add additional powdered sugar (¼ c at a time). If it's too thick, add additional milk (1 teaspoon at a time). You can also add additional mint extract and/or coloring if you'd like.
Use a knife or a piping bag to top the cooled cupcakes with frosting and garnish with additional cookies.