In a medium-sized bowl, whisk together the flour, cocoa powder, baking soda, espresso powder/instant coffee, and salt. Set the bowl aside.
In the bowl of a stand mixer, cream the butter and sugars together for a few minutes, until they are light and fluffy. Beat in the eggs, one at a time, allowing for each egg to incorporate completely, and add the vanilla and peppermint extracts.
Little by little, add the dry ingredients to the wet, on low speed. Scrape down the sides of the bowl as necessary. Add the mini chocolate chips. Turning the speed up a bit higher helps to incorporate them throughout the thick, sticky dough.
Next, you need to chill the dough. Cover the dough tightly with plastic wrap (you can chill it right in the bowl of the stand mixer, or transfer to another bowl if you want. Chill the dough for at least 3 hours, and up to overnight.
After chilling, let the dough sit out at room temperature for 20-30 minutes. While the dough warms up a little, preheat the oven to 350 degrees F and line two baking sheets with parchment paper.
Scoop and roll cookie dough into 1.5 tbs-sized balls balls. Place them on the baking sheets, leaving a couple of inches between cookies.
Bake the cookies for 9-10 minutes. Remove them from the oven and allow them to cool on the cookie sheets for 5 minutes or so before removing them to a wire rack to finish cooling completely.
Once the cookies have cooled, melt the white chocolate. Dip the cookies into the chocolate, or drizzle chocolate over the cookies, and sprinkle with crushed candy canes.
Chilling the dough is very important. If you don't chill the dough, the cookies will spread waaay too much. Trust.