In a bowl, combine flour, baking powder, and salt.

In a larger bowl, beat butter, brown sugar, and sugar with an electric mixer until mixture is light and puffy.

Add egg, zest, and vanilla while beating. Turn mixer to low speed and stir in the dry ingredients.

Divide the dough in half and shape each portion into a disc. Wrap each dough disc with plastic wrap and refrigerate for 1 hour.

Make little balls with the dough and place them on a baking sheet. Press them a little with your hand.

Bake in a preheated oven at 350°F for about 12 minutes or until bottom and edge of cookies are lightly browned.

Place on a rack and let cool for 1 minute.