Step 1: Preheat oven to 350°F (175°C) and line baking sheets with parchment paper.
Step 2: In a medium bowl, whisk together flour, baking powder, and salt.
Step 3: In a large bowl, cream butter and sugar until light and fluffy.
Step 4: Beat in egg, coffee mixture, and vanilla extract until well combined.
Step 5: Gradually add dry ingredients to wet ingredients, mixing until just combined.
Step 6: Shape dough into 1-inch balls and roll in additional sugar.
Step 7: Place cookies 2 inches apart on prepared baking sheets.
Step 8: Bake for 10-12 minutes until edges are lightly golden.
Step 9: Let cool on baking sheets for 5 minutes before transferring to wire racks.