In a medium sized bowl combine flour, cocoa powder, baking soda and salt.
Using a stand mixer or hand mixer beat butter and sugars together until fluffy. Add the egg and peppermint extract and combine.
Gradually add the dry ingredients to the butter mixture and combine using the lowest speed. Stir in white chocolate chips.
Chill the dough for a couple of hours.
Preheat the oven to 180°C. Line a baking tray with baking paper or a Silpat liner and set aside.
Using a cookie scoop or spoon create balls of dough about 1 ½ tablespoon in size. Roll ball in the chopped candy canes and place on the prepared baking tray about 5cm apart. Flatten slightly with a fork.
Bake for 10-12 minutes until set, checking after 10 minutes. You don't want to overbake the cookies. Let the cookies sit on the baking tray for 5-10 minutes before moving to a cooling rack.