Preheat oven to 350 degrees.  Line cookie sheets with parchment paper or a non stick baking mat.

Cream together the butter and granulated sugar until light and fluffy, about 3 minutes.  Add egg and mix until well-combined.

Stir in flour, baking powder, salt, vanilla, lemon zest and lemon juice.  Allow to sit for about 3 minutes to allow lemon flavor to develop.

Scoop cookie dough by the tablespoon full and roll into ball.

Add Lemon Sugar to a large bowl for rolling cookie in before baking.  Place each ball of cookie dough into the bowl of lemon sugar and roll to coat well.   Place cookie onto baking sheet, spacing about 1 1/2 to 2 inches apart.  Lightly press each cookie down.  Bake for 10 - 12 minutes or until lightly browned.

Lemon Sugar 

1/2 cup granulated sugar

Zest of one large lemon

Stir together granulated sugar and lemon zest.  Store leftover, if any, in an airtight container  for future use