3 cups all-purpose flour, plus more for surface
1/2 teaspoon salt
8 ounces (2 sticks) unsalted butter
1/2 cup granulated sugar
1/2 cup light brown sugar
1 large egg yolk
3/4 cup maple syrup (preferable grade A)
Vegetable oil cooking spray
1/3 cup sanding sugar
Sift flour and salt into a medium bowl.
Beat butter and granulated and brown sugars with a mixer on medium-high speed until pale and creamy, about 3 minutes.
Reduce speed to medium-low, and add yolk, then 1/2 cup maple syrup, beating well after each addition.
Add flour mixture, and beat until just incorporated.
Shape into 2 disks, wrap each in plastic, and refrigerate for at least 2 hours (or up to 2 days).
Preheat oven to 325 degrees.
Roll out 1 disk of dough to 1/4-inch thickness on a sheet of lightly floured parchment.
Place parchment with dough on baking sheet.
Freeze until firm, about 15 minutes.
Coat baking sheets with cooking spray, line with parchment, and coat parchment.
Cut out cookies from frozen dough using a 3 1/2-inch maple-leaf-shaped cutter, and space 1 inch apart on sheets.
Roll and cut scraps once.
Freeze cookies until firm, about 15 minutes.
Bake cookies until edges begin to turn golden, 14 to 16 minutes.
Transfer parchment with cookies to wire racks, and let cool for 5 minutes.
Brush cookies with 2 tablespoons maple syrup, and sprinkle with 1/2 the sanding sugar.
Repeat with remaining dough, maple syrup, and sugar. (Cookies will keep for up to 2 days.)
Makes about 8 dozen.