Preheat oven to 350 and line a cookie sheet with parchment paper. (You can make 2 batches at the same time if more baking sheets are available.)
Beat butter and sugar together for two minutes in an electric mixer on medium-high speed.
Scrape sides and bottom of the bowl and beat for another minute.
Scrape sides and bottom of the bowl again and beat in egg and vanilla extract on medium speed.
Lower speed to low and add flour and baking powder. Beat just until combined.
Scrape sides and bottom of the bowl and make sure all ingredients are evenly mixed.
Scoop cookie dough with a cookie scoop (you can use #50 or #40 cookie scoop). Quickly but gently roll it into a ball and gently press to flatter it only slightly.
Roll each cookie ball in white granulated sugar.
Place cookie dough balls on prepared cookie sheet, about 2 inches apart.
Bake for 10-12 minutes, depending on the size of the cookie.