Combine the butter and sugar together in the bowl of an electric mixer. Blend until light and fluffy.
Add the egg and vanilla to the butter mixture. Mix until combined.
Sift the flour and baking powder together. With the mixer on low speed, spoon the flour mixture into the butter mixture.
Cover the dough and chill for 1 hour.
Preheat the oven to 375°F and line 3 baking sheets with parchment paper.
Scoop and shape the dough into 1-inch balls. Roll the shaped dough into decorative sugar. Place the cookies on the lined baking sheets. Using the back of a spoon, press the top of each cookie until just slightly flat.
Bake for 8 to 10 minutes. Remove from the oven and remove the cookies from the cookie sheet to a cooling rack.
This recipe was calculated using the exact brands and measurements I used to make this recipe. If you are following a strict diet please note changing anything will cause the nutritional info to change. My calculations are intended as a guide only.