01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together the all-purpose flour, baking powder, and salt until evenly distributed.
03 - In a large bowl, beat the softened butter and granulated sugar together using an electric mixer until the mixture is light and fluffy, approximately 2 to 3 minutes.
04 - Add the egg and vanilla extract to the creamed butter mixture. Beat until fully combined and smooth.
05 - Gradually add the dry ingredient mixture to the wet ingredients, mixing until just incorporated. Be careful not to overmix the dough.
06 - Scoop tablespoon-sized portions of dough and roll into even balls. For a sparkling crystallized finish, roll each ball in the extra granulated sugar.
07 - Place the dough balls 2 inches apart on the prepared baking sheets. Flatten each ball slightly using the bottom of a glass or the palm of your hand.
08 - Bake for 8 to 10 minutes, until the edges are just turning golden. Allow the cookies to rest on the baking sheet for 2 minutes, then transfer to a wire cooling rack to cool completely.