Preheat oven to 350 F and line baking sheet with parchment paper.
Crush 5 candy canes. I like to do this by placing the candy canes in a zip lock back and hitting them with the back of a metal spoon. You want the pieces to be quite small. Set aside after crushed.
In a medium sized bowl whisk flour, cocoa powder, salt, baking powder, and baking soda together. Set aside.
In a large bowl cream together butter and sugars until light and fluffy. This usually takes 2-3 minutes.
Add in egg, egg yolk, and peppermint extract and mix till combined.
Add the flour mixture in and mix till just combined.
Fold in the chocolate chips and crushed candy canes.
Scoop 1 & ½ tbsp worth of the cookie dough and shape into a ball. Place the cookies 2 inches apart on the baking sheet.
Bake for 8-9 minutes or until edges are firm. The cookies will still be soft but will firm up after cooling.
Once cookies are completely cooled melt chocolate chips in the microwave in 20 second increments, stirring in between each time, until smooth.
Crush two more candy canes.
Pour melted chocolate into a piping bag or a zip lock bag. Cut a small pieces off the corner and drizzle chocolate on the cookies.
Sprinkle the crushed candy canes on top of the melted chocolate. Let sit until chocolate is set.
