Heat oven to 350 degrees Fahrenheit.
Using a stand or hand mixer, cream butter and sugar until combined. Add egg, peppermint extract, and chocolate and mix until combined. Add flour, cocoa powder, baking powder, baking soda, and salt and mix until combined. Add 3/4 cup white chocolate chips and 1/2 cup crushed candy canes and mix until combined.Grease Holy Sheet (or another baking sheet) and an 8-inch cake ring or 8-inch cake pan, and press cookie dough mixture evenly across surface.Bake for 20 minutes. Immediately after removing the cookie pie from oven, decorate your cookie pie by sprinkling remaining white chocolate chips and crushed candy canes around the outer edge of the entire cookie pie.
Cool completely before slicing into 8-10 pieces.To make Pretzel Crumb:
Heat the oven to 275 degrees Fahrenheit.
In a bowl, crush the pretzels until they're about the size of Rice Krispies. Add and toss the pretzel pieces with the sugars, milk powder, and malt powder. Add the melted butter and toss to coat all dry ingredients.Spread small clusters of the crumbs onto a parchment or Silpat-lined sheet pan and bake for 20 minutes. They should look lightly toasted and smell buttery. Cool completely before storing in an airtight container.