In a medium bowl, combine butter, confectioners’ sugar, and granulated sugar. Beat at medium speed with a mixer until creamy. Add lemon zest, lemon juice, vanilla extract, and egg, beating until well combined.
In a small bowl, combine flour and salt. Gradually add flour mixture to butter mixture, beating to combine. Cover, and refrigerate for 1 hour.
Preheat oven to 350°. Line 2 baking sheets with parchment paper.
Roll dough into 1-inch balls. Place dough 2 inches apart on prepared baking sheets. Using a flat-bottomed glass dipped in sugar, flatten dough to a ¼-inch thickness. Bake for 12 to 14 minutes or until lightly browned. Let cool on pans for 5 minutes.
Roll in confectioners’ sugar. After cookies have cooled completely, roll in confectioners’ sugar a second time.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/lemon-coolers-recipe/