In a medium bowl, whisk together the flour, cocoa powder, cornstarch, baking soda, espresso powder, and salt until combined. Set aside.
In the bowl of an electric stand mixer fitted with a paddle attachment, cream the butter until smooth. Add in both sugars and mix on high for 3 minutes until light and fluffy. Add the eggs one at a time, mixing after each addition until combined. Add in the vanilla and peppermint extract.
With mixer set on low speed, slowly add the flour mixture into the wet mixture until everything has been incorporated. Remove bowl from the mixer, and stir in the chocolate chips, Oreos, and 3/4 of the Hershey kisses. The rest will be added to the tops of the cookies when they come out of the oven.
Cover dough tightly and chill in the refrigerator for at least 30 minutes and up to 3 days.**
Preheat the oven to 350ºF and line a baking sheet with parchment paper. Roll the dough into balls about the size of a golf ball, then place them on the baking sheet about 2 inches apart. Flatten each dough ball slightly so that it resembles a little hockey puck.
Bake for 8-10 minutes, or until the edges are set and the centers are puffy but still look slightly underdone. Immediately after they come out of the oven, press more chocolate chips and Hershey kisses into the tops. Allow cookies to cool on the baking sheet for 10 minutes before transferring to a wire rack to cool completely.