Preheat oven to 350°F. In a medium bowl, whisk flour, baking powder, and salt until combined.
In a separate bowl, cream butter and sugar until light and airy, about 2 minutes.
Beat in egg and vanilla until glossy. Gradually mix in dry ingredients until a smooth dough forms. Chill 30 minutes.
Scoop tablespoons of dough onto parchment-lined baking sheets, flatten slightly. Bake 9–11 minutes until edges are set.
Icing & Assembly
Whisk powdered sugar, milk, vanilla, and corn syrup until smooth. Let cookies cool completely.
Spread or pipe white icing on cookies. Use black gel to add eyes and mouths. Allow to set 60 minutes.
Notes
Personal Testing Note: Extending the creaming time by 30 seconds yielded a silkier dough.Personal Testing Note: Pulling cookies from the oven at exactly 9 minutes gave tender centers with crisp edges.Personal Testing Note: Freezing baked cookies in an airtight container preserved the icing sheen best.