- 2 cups all-purpose flour
- 1 1/4 teaspoons coarse salt
- 2 sticks unsalted butter, softened, plus more for pan
- 3/4 cup confectioners' sugar
Preheat oven to 300 degrees. Sift together flour and salt into a medium bowl. Beat butter with a mixer on medium-high speed until fluffy, 3 to 5 minutes, scraping down sides of bowl with a rubber spatula as needed. Add sugar gradually, beating between additions; continue to beat until mixture is very pale, about 2 minutes total. Reduce speed to low, and add flour mixture; beat until just combined.
Press dough evenly into a parchment-lined 9-by-13-inch rimmed baking sheet; refrigerate until firm, about 20 minutes. Cut dough in eighths lengthwise, then quarters crosswise, making 32 rectangles. Evenly pierce all over with a skewer.
Bake until shortbread is firm in center and golden brown, 50 minutes to 1 hour. Transfer pan to a wire rack; immediately recut rectangles with a paring knife. Let shortbread cool completely in pan.