Preheat oven to 350 degrees. Line a 9x13 with aluminum foil and spray with cooking spray. Set aside. In a medium sized mixing bowl, combine flour, baking powder, and salt. Set aside.
Chop the unsweetened chocolate and add it to a microwave safe bowl. Add the butter and microwave 30 seconds at a time stirring in between until melted and smooth. Set aside.
In a stand mixer beat the eggs, sugar, and vanilla for two minutes. Slowly add the melted chocolate until incorporated and add the flour mixture. Mix until just combined and pour into the 9x13 inch pan. Bake for 20-30 minutes or until toothpick comes our clean. Let brownies completely cool on a wire rack and put in the fridge to chill.
To make the Mint frosting, beat together powdered sugar, butter, peppermint extract, milk and red food coloring until fluffy. Spread evenly over the top of the brownie layer and put in the fridge to chill.
To make the chocolate ganache: In a microwave safe bowl add the chocolate chips and butter. Cook in 30 second intervals stir until melted. Spread evenly over the mint frosting layer.
Sprinkle the crushed candy canes on top and chill until the chocolate has hardened.