Preheat oven to 350 degrees
Using a standing mixer, prepare the brownie mix according to the box
Bake in the oven for 20 minutes
While the brownies are baking, prepare the frosting
Using the standing mixer, combine all ingredients and mix on medium speed until combined and smooth
Scoop frosting into the piping bag
Once the brownies are baked, let cool to room temperature
Once the brownies are cooled, pipe the frosting around the brownies
Using a flat spatula or knife, smooth the frosting out over the brownies
Set aside while you make the chocolate ganache
Using a small sauce pan, heat up the heavy whipping cream until it start to simmers
Pour the chocolate chips into a medium bowl
Pour the heavy whipping cream over the chocolate chips and let sit for a few minutes
Using a whisk, mix until smooth
Pour ganache over the frosting
Using a ziplock bag and a rolling-pin, crush up the mint cookies into crumbles
Sprinkle the crushed cookies over the ganache
Place into the fridge for an hour or until ganache hardens
Cut into bars and enjoy!