In a medium bowl whisk together flour, cocoa powder, baking soda, and salt. In a large bowl beat together butter, brown sugar, and sugar until light and fluffy (2-3 minutes). Mix in egg and vanilla until blended.
Gradually mix in dry ingredients on low speed until just incorporated, don't over mix. Stir in the chocolate chips by hand. (I reserve 1/4 cup for adding at the end) Cover TIGHTLY and chill for 2 hours or overnight.
Preheat oven to 350 degrees and take the dough out of the fridge while the oven is preheating.
Roll 2-3 tablespoons of cookie dough into a ball. Break the ball in half and place one half on a baking sheet. Top with second half of the dough ball and press down to flatten slightly. Press a few extra chocolate chips in the top (optional). Repeat with remaining dough and place on a lightly greased baking sheet two inches apart.
Bake for 10-12 minutes until the tops of the cookies are just set. Allow to cool on the baking sheet for 5 minutes before transferring to a cooling rack to cool completely.
Once cookies are cooled, place peppermint candies in a microwave safe bowl and microwave on half power for two minutes. Stir, return to microwave in half power in 20 second increments stirring after each until smooth.
Dip cookies into melted peppermint candy, then place on a parchment or wax paper-limed baking sheet and immediately sprinkle with crushed candy canes. Allow to cool until hardened (about 5 minutes if you place it in the fridge or freezer). Store in airtight container up to 5 days (best served by 3 days).