Preheat the oven to 350°F.
Prepare the cookies: Add the flour, cocoa powder, salt, baking soda and baking powder to a medium bowl and whisk to combine.
In a separate bowl, or in the bowl of a stand mixer, beat the butter, brown sugar and regular sugar until light and fluffy (this should take about 3-4 minutes). Add the eggs, vanilla extract and peppermint extract and beat until incorporated.
Add the 1/3 of the flour mixture at a time along with the crushed candy canes and beat until mixed in. Make sure not to over mix at this time.
Use a 1 ½ Tbsp cookie scoop to scoop cookie dough and roll into balls. Place cookie dough onto parchment paper lined cookie sheet 2 inches apart. Bake for about 7-10 minutes , or until edges are set and the tops are nice and puffy.(8 minutes is my magic number)
Remove the cookies from the oven and use a biscuit cutter or cookie cutter to scoot the cookies into nice even circles--totally optional but makes them so pretty! Cool for several minutes before transferring to a wire rack to finish cooling.
Make the ganache: Chop the dark chocolate and place in a small bowl with the espresso powder. Warm the heavy cream up in the microwave in 20 second increments until hot, but not boiling. I heated for about 40 seconds.
Pour the cream over the chocolate and allow it to sit for a few minutes and then stir it until the chocolate is melted and its smooth. If your chocolate won't completely melt, pop it in the microwave for another 5-10 seconds and then stir.
Spoon the ganache onto each of the cooled cookies. I used roughly 3/4 teaspoon for each and had enough for all of the cookies. Sprinkle over crushed candy canes or favorite toppings. Allow the cookies to set for about 1 hour--or eat them immediately like I did!