Preheat oven to 350 degrees F. Line a 9×13 baking pan with parchment paper and spray lightly with nonstick cooking spray.
In a medium bowl, combine flour, baking powder and salt. This is the dry mixture.
In a stand mixer bowl, mix the butter and sugar for 1 minute. Add the egg and vanilla extract and mix again.
While the stand mixer is on low speed, add the dry mixture and combine until the dough comes together. Press the dough onto the pan and make sure that the surface is even.
Bake for 20-25 minutes or until the sides are golden brown. Remove and cool completely on a baking rack.
Ganache
In a medium saucepan, heat up the milk just to a boiling stage. Remove from heat. Add the chocolate and DO NOT STIR for 5 minutes.
After 5 minutes, whisk the chocolate until it becomes a smooth mixture. Cool for 10 minutes in the pan.
Pour the ganache over the sugar cookie bar and spread evenly. Sprinkle with the crushed candy canes. Chill for about 2 hour or overnight before cutting it into bars.