Whisk together flour, baking powder, baking soda, and salt in a medium bowl. Set aside.

In a large mixing bowl, cream together butter and sugar until fluffy and pale yellow. Add egg and keep mixing until smooth. Beat in lemon zest, lemon juice, and Greek yogurt.

Stir in dry ingredients, making sure not to overmix.

Scoop out dough using a large cookie scoop and place on the prepared baking sheet 2 inches apart.

Bake for 15-18 minutes or until edges are just beginning to brown.

Allow to cool on the sheet pans for about 5 minutes before removing to a cooling rack to complete cooling.

To make the glaze, add all ingredients to a small bowl and stir until smooth. If icing is too thick, very gradually add small amounts of milk.

Once the cookies have completely cooled, smooth a think layer of glaze on top.