Preheat the oven to 350 degrees.* Line a large baking sheet with parchment paper (I usually need to make this dough in two batches since I can only fit about 6 cookies on my baking sheet.)
With a stand mixer or hand mixer, beat the butter until it is light and fluffy. Next, add in the sugar and brown sugar, beating until combined.
Add in the egg, and beat until combined.
Next, add in the peppermint extract and vanilla extract, mixing until combined.
Add in the espresso powder, baking soda, and salt. Mix until combined.
Next, add in the flour and cornstarch, mixing until combined.
Lastly, add in the crushed candy canes, chopped peppermint bark, and chocolate chips (both semi-sweet and dark chocolate). Once combined, use a large cookie scoop to scoop the dough and place evenly apart on the prepared baking sheet.
Bake for 13-15 minutes, or until the cookies are just set in the centers.
Once the cookies are cooling, add extra peppermint bark on top and a sprinkling of sea salt on top, if desired.