Preheat oven to 350 degrees. Line a baking sheet with parchment paper.
To prepare Kahlua sugar: in a small bowl with a fork mix Kahlua into granulated sugar until incorporated. Set aside.
To make cookies: In a medium sized bowl whisk together flour, cocoa powder, baking powder and espresso powder, set aside. In your mixing bowl, cream together the butter, sugar, coffee extract, and Kahlua for about 4 minutes. Mixture will be light and fluffy. Add eggs, one at a time, beat until incorporated. Gradually fold in flour mixture until well combined.
Scoop out Tablespoon sized portions of dough, roll into a ball, roll in Kahlua sugar, and place on parchment lined cookie sheet.
Bake cookies for 10-12 minutes. Tops will be cracked and cookies will be puffy. Cool on rack. Enjoy!