Preheat oven to 350F. Line or spray two large baking sheets. In a large bowl with a stand or electric mixer, cream together butter, brown sugar, and sugar until light and fluffy, 1-2 minutes. Add eggs, vanilla, and peppermint. Mix until batter has lightened in color, 2-3 minutes.

In a separate bowl, whisk together flour, cocoa powder, baking soda, and salt. Toss in mini chocolate chips. Add dry ingredients to wet ingredients and mix until combined. Place powdered sugar in a bowl or shallow dish.

Scoop dough into heaping Tbsp-sized balls and roll into a smooth ball shape (if dough is too sticky, let rest for 10-15 minutes or refrigerate a few minutes). Roll each ball in the powdered sugar, shaking off the excess, and place several inches apart on the baking sheets.

Bake 9 minutes, until puffed and crackled. Remove baking sheet from oven. Immediately press an unwrapped Hershey's Kiss into center of each cookie. Remove the cookies to a wire rack to cool completely.