Preheat oven to 350 degrees. Line a baking sheet with parchment paper or silicone baking mat and set aside.
Zest and juice lemon (depending on how juicy your lemon is, you may need more than one).
In a clean bowl whisk together flour, baking powder, baking soda and salt.
Using a hand-held or stand mixer with a paddle attachment, cream the butter and sugar. Add vanilla, lemon zest, lemon juice and egg and beat 2 minutes.
Stir in dry ingredients slowly, just until combined. Dough will be pretty wet.
Plop scoops of dough onto a lined baking sheet, about 1 ¼ inch diameter. Bake 9-11 minutes just until the tops of the cookies turn matte. (not shiny or melted looking). Cool for 5 minutes before moving to a cooling rack.
Allow to cool at least 10 minutes. Meanwhile, combine powdered sugar and lemon juice to form the tart lemon glaze. Start with ½ cup and add a little more until the desired consistency is reached.
Using a spoon, fill it with glaze and allow it to drizzle over the cookie. These cookies are meant to be fun, so don't worry about a specific design!
Enjoy!
Notes
Make ahead: The dough can stay in the refrigerator for up to 3 days, just let it rest on the counter for 30 minutes before use. Cooked cookies can be frozen for up to 1 month.Store leftovers in an airtight container at room temperature up to 3 days. Soften in the microwave for about 8 seconds, if desired.Use a microplane for easy lemon zesting! Use a citrus juicer to get the most juice out of your lemon.Take the time to cream the butter and sugar together for the full amount of time. People ask me all the time why my cookies are so good and this is my numer one tip for the best texture of cookie!Don't over bake these cookies! They are done when the tops are completely matte and the edges are set. After removing from the oven, allow them to finish baking on the baking sheet for 5-10 minutes.