01 - Cream softened butter and powdered sugar in large bowl until light and fluffy using electric mixer.
02 - Blend lemon juice, lemon zest, and vanilla extract into butter mixture until fully incorporated.
03 - Mix salt, flour, and cornstarch into wet ingredients until soft dough forms.
04 - Divide dough in half, roll each into 1-inch diameter logs, wrap in plastic, and refrigerate 30 minutes.
05 - Preheat oven to 350°F and line baking sheets with parchment paper.
06 - Unwrap chilled dough and slice into 1/4-inch rounds, placing 1 inch apart on prepared sheets.
07 - Bake 10-12 minutes until edges barely golden.
08 - Let cool 5 minutes on sheets, then gently toss in powdered sugar while warm.
09 - Cool completely on wire rack, dusting with additional powdered sugar before serving.