01 - In a large bowl, cream together softened butter and 1/2 cup powdered sugar until light and fluffy using an electric mixer.
02 - Mix in lemon juice, lemon zest, and vanilla extract until fully incorporated into the butter mixture.
03 - Add salt, flour, and cornstarch, mixing until a soft dough forms. Be careful not to overmix.
04 - Divide dough in half and roll each half into a 1-inch diameter log. Wrap in plastic wrap and refrigerate for at least 30 minutes.
05 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
06 - Unwrap chilled dough and slice into 1/4-inch rounds. Place on prepared baking sheets, spacing 1 inch apart.
07 - Bake for 10-12 minutes until edges are just barely golden. Watch carefully to prevent overbrowning.
08 - Let cool on baking sheets for 5 minutes. While still warm, gently toss cookies in powdered sugar to coat evenly.
09 - Transfer cookies to a wire rack and cool completely. Dust with additional powdered sugar before serving for extra presentation.