01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, and salt until well blended.
03 - In a large bowl, beat softened butter and granulated sugar with an electric mixer until light and fluffy, approximately 2-3 minutes.
04 - Beat in eggs one at a time, ensuring each is fully incorporated. Add lemon juice, lemon zest, and vanilla extract, mixing until combined.
05 - Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed until just incorporated. Do not overmix.
06 - Drop rounded tablespoons of dough onto prepared baking sheets, spacing cookies 2 inches apart to allow for spreading.
07 - Bake for 10-12 minutes, or until edges are lightly golden and centers are set.
08 - Allow cookies to cool on baking sheets for 5 minutes, then transfer to wire racks to cool completely before frosting.
09 - Whisk powdered sugar, lemon juice, lemon zest, and melted butter until smooth and spreadable. Adjust consistency with additional lemon juice if needed.
10 - Spread lemon frosting over cooled cookies. Let frosting set for 15 minutes before serving.