Preheat oven to 350º. Line a 9x13 inch pan with foil, making sure the foil extends over the edges by at least one inch. Lightly spray foil with nonstick cooking spray and set aside.
Combine flour, baking powder, and salt. Set aside.
Chop the baking squares and butter into chucks and place in a microwave-safe bowl. Microwave in 30 second intervals, stirring in between, until just melted and smooth. Set aside to cool, stirring occasionally.
In a stand mixer or with electric beaters, beat eggs, sugar and vanilla for 2 minutes. While the mixer is running, slowly add the melted chocolate and beat to combine. With the mixer on low speed, gradually add flour mixture and mix just until combined. Pour into prepared 9x13 pan.
Bake for 20-30 minutes or until a toothpick poked in the center comes out mostly clean. Don’t over bake! When brownies are done, cool on a wire rack. When completely cool, put in the fridge to chill (makes the frosting spreading easier).
Peppermint frostingCombine all frosting ingredients and beat until light and fluffy. Add more milk a teaspoon at a time if needed. Spread evenly over chilled brownies and place back in the fridge to chill again while you do the final step. (I used an offset spatula to spread the frosting.)
Chocolate GlazePlace chocolate chips and butter in a microwave-safe bowl. Microwave in 30 second intervals, stirring in between, until just melted and smooth. Set aside to cool for about 15 minutes, stirring occasionally, and then quickly spread on top of brownies.
Sprinkle the crushed candy canes on top and return to the fridge to cool. When chocolate has hardened, use the edges of the foil to remove the entire sheet of brownies from the pan. Cut into squares and serve.