01 - Preheat oven to 350°F. Line two baking sheets with parchment paper and set aside.
02 - In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until evenly distributed. Set aside.
03 - In a large bowl, beat the softened butter and granulated sugar together using an electric mixer on medium speed until light and fluffy, approximately 2 to 3 minutes.
04 - Add the egg, lemon zest, freshly squeezed lemon juice, and vanilla extract to the butter mixture. Beat until well combined and smooth.
05 - Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed until just incorporated. Be careful not to overmix.
06 - Scoop tablespoon-sized portions of dough and roll into balls. Place on the prepared baking sheets, spacing each about 2 inches apart to allow for spreading.
07 - Bake for 10 to 12 minutes, or until the edges are lightly golden. Allow cookies to rest on the baking sheets for 5 minutes, then transfer to a wire cooling rack to cool completely.
08 - In a small bowl, whisk together the powdered sugar and lemon juice, adding the juice gradually until the desired drizzling consistency is reached. Stir in additional lemon zest if desired for extra flavor.
09 - Drizzle or spread the glaze evenly over the completely cooled cookies. Allow the glaze to set at room temperature before serving.