In a medium bowl, whisk together the flour, cocoa, baking powder, and salt. Set aside.

In a mixing bowl, beat the butter, sugar, and brown sugar together until fluffy, scraping down as needed, for about 3-4 minutes.

Add the egg and the peppermint extract, beating until just blended.

Slowly add the flour mixture to the butter mixture and beat until just mixed, scraping down as needed.

Cover and refrigerate the dough for at least 1 hour.

Preheat the oven to 350 degrees.

Prepare a large baking sheet with parchment paper.

Using a small cookie scoop, drop mounds of cookie dough on the prepared baking sheet about 2-inches apart.

Bake the cookies for 11 minutes (for chewier cookies) to 14 minutes (for crispier cookies.)

Allow to cool completely on a wire rack before adding the chocolate coating.

In a large microwave-safe bowl, place the chocolate chunks and shortening.

Heat for 1 minute on high in the microwave and stir vigorously to allow the chocolate to continue melting from the residual heat.

Repeat in 30-second increments if needed, taking care to not overheat and seize the chocolate. Stir in the peppermint extract.

Prepare a baking sheet with parchment paper.

Dip the bottoms of the cookies in the melted chocolate.

Using a fork and a spoon, spoon additional chocolate over the top of the cookie, scraping the spoon across the bottom and top to remove any excess chocolate.

Transfer the cookies to the prepared baking sheet.

Refrigerate the cookies until the chocolate is set.