Preheat the oven to 350˚F. Line an 8x8 inch baking pan with parchment paper, leaving a slight overhang on two edges. Set aside.
In a medium saucepan, melt the butter. Remove from heat and mix in the sugar, eggs and vanilla. Add in the cocoa powder, flour, salt and baking powder and mix until just combined.
Pour the batter into the prepared pan and bake in the preheated oven for 25-30 minutes,or until a toothpick inserted in the centre comes out with a couple of crumbs.
Remove from oven and allow to cool completely in the pan.
When the brownies are cool, place the white chocolate and shortening in a microwave safe bowl. Heat for 1-1.5 minutes in the microwave, removing from the microwave every 30 seconds to stir until smooth. Do not overcook!
Pour the melted chocolate over the cooled brownies. Sprinkle with the crushed candy canes. Place in the fridge until the chocolate has hardened.
Using a very sharp warm knife (run it under hot water and wipe dry), cut the brownies into 9 squares, then again diagonal through each square to give you 18 triangles. Store in an airtight container.