Whisk together the flour, baking powder, and salt.
In a stand mixer, cream together the butter, granulated sugar, and lemon zest.
Add the egg and vanilla extract and beat for 1 minute.
Add the dry ingredients to the butter mixture and mix until just combined.
Scoop the dough into balls, flatten them to ½ inch thickness, and bake at 350°F for 15-17 minutes.
Let the cookies cool completely.
Make the glaze by mixing the powdered sugar and 2-4 Tbsp lemon juice until desired consistency.
Spread the glaze over the cooled cookies and top with additional lemon zest.
