01 - Preheat oven to 350°F and line a baking sheet with parchment paper.
02 - In a large mixing bowl, beat unsalted butter and powdered sugar together until light and fluffy.
03 - Incorporate fresh lemon juice, lemon zest, and vanilla extract into the creamed butter mixture, blending thoroughly.
04 - In a separate bowl, whisk all-purpose flour, cornstarch, and salt. Gradually fold dry ingredients into the butter mixture, mixing until a soft dough forms.
05 - Portion dough into tablespoon-sized balls and place onto prepared baking sheet. Gently flatten each ball with your fingers.
06 - Bake for 10 to 12 minutes or until just set and pale in color. Remove baking sheet from oven and allow cookies to cool for 5 minutes before transferring to a wire rack.
07 - In a small bowl, whisk powdered sugar and fresh lemon juice together until completely smooth. Add lemon zest if additional flavor is desired.
08 - Drizzle or dip each cooled cookie in lemon glaze. Allow glaze to set for 15 minutes before serving.