1. Preheat oven to 325°. Put flour, butter, granulated sugar, and salt in the bowl of a stand mixer. Mix on low speed until blended, then increase to medium and mix until dough is no longer crumbly and just comes together.
2. Press dough evenly into a 9-in. round cake pan. Sprinkle with coarse sugar.
3. Bake until golden brown, 30 to 40 minutes. Cut still-warm shortbread with a fork, tines down, into 16 wedge-shape pieces with shaggy edges. Cool completely, then invert pan onto a work surface and carefully separate cookies.
*Find coarse sugar in the baking aisle.
Make ahead: Up to 5 days. Store airtight up to 1 week.
Note: Nutritional analysis is per cookie.