01 - Preheat the 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 mixing bowl, beat the softened butter and granulated sugar together using an electric mixer 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. Do not overmix.
06 - Scoop tablespoon-sized portions of dough and roll into balls. Place on the prepared baking sheets, spacing them 2 inches apart to allow for spreading.
07 - Bake for 10 to 12 minutes, or until the edges are lightly golden. Allow the 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 the powdered sugar with 2 to 3 tablespoons of freshly squeezed lemon juice, adding the juice gradually until the desired drizzling consistency is reached. Stir in additional lemon zest if desired.
09 - Drizzle or spread the glaze over the completely cooled cookies. Allow the glaze to set at room temperature before serving.