Lemon-Lime Basil Shortbread Cookies
1 cup all-purpose flour
1/2 cup powdered sugar plus more for pressing cookies
1/2 cup (1stick) chilled unsalted butter, cut into 1/2' cubes
2 tablespoons sliced fresh basil leaves
1 teaspoon finely grated lemon zest plus 1 tablespoon fresh lemon juice
1/2 teaspoon finely grated lime zest
1/4 teaspoon kosher salt
Sanding sugar (optional)
Preheat oven to 375°. Place flour, 1/2 cup powdered sugar, butter, basil, both zests, lemon juice, and salt in a food processor. Pulse until large, moist clumps form. Measure level tablespoonfuls of dough; roll between your palms to form balls. Place on a large baking sheet, spacing 2" apart. Lightly dust the bottom of a flat measuring cup with powdered sugar and press cookies into 2" rounds, dusting cup bottom with powdered sugar as needed to prevent sticking. Sprinkle tops of cookies with sanding sugar, if using.
Bake until edges are brown, about 14-15 minutes. Transfer to a wire rack; let cool.