Preheat oven to 350°. Line a baking sheet with parchment paper.
In a large bowl, combine flour, 1 tablespoon sugar, lemon zest, and salt. Using a pastry blender, cut butter into flour mixture. Combine until a dough forms.
On a lightly floured surface, roll dough to a ¼-inch thickness. Using a 1-inch heart-shaped cutter, cut 8 shapes from dough. Place hearts on prepared baking sheet. Reroll scraps, if necessary. Sprinkle with remaining 1 tablespoon sugar. Bake until lightly browned, 8 to 10 minutes. Let cool on pan for 2 minutes. Transfer to a wire rack, and let cool completely. Store in an airtight container.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/lemon-custard-with-shortbread-cookies-recipe/