Makes about 2 dozen.
1 cup (2 sticks) unsalted butter, softened
1/4 cup superfine sugar
1 large egg
1 tablespoon pure vanilla extract
2 cups bleached all-purpose flour
1/8 teaspoon salt
Combine the butter and the sugar in a large bowl. With an electric mixer set at medium-low speed, beat the butter and sugar together until the mixture is creamy and the grains of sugar are barely visible, 2 to 3 minutes. Add the egg and vanilla extract and beat until the mixture is smooth and combined.
Sift the flour and salt into the butter mixture. Using a large wooden spoon, stir the flour into the butter until incorporated. (Mixing the flour in by hand instead of using the electric mixer avoids overworking the dough, which would make the cookies hard and tough.)
Divide the dough in half. On a sheet of wax paper, form each half into a 10-inch log, using the paper to help form a smooth cylinder. Wrap tightly in the waxed paper and refrigerate for at least 2 hours or up to 1 week. For longer storage, wrap the logs a second time in plastic wrap and freeze for up to 1 month.
Place an oven rack on the middle shelf of the oven. Preheat the oven to 325 degrees F. Line a baking sheet with parchment paper.
Using a long, sharp knife, slice the dough into 1/2-inch-thick rounds and place them on the prepared pan. Bake for 12 to 15 minutes, or until the edges of the cookies are a pale, golden brown but the centers of the cookies are still very pale. Remove the cookies from the baking sheet with a large metal spatula and let cool completely on a wire rack.
Store sables in a tightly covered container for 2 to 3 days.
Follow the recipe for Vanilla Sables, using 1 3/4 cups flour and 1/3 cup unsweetened Dutch-processed cocoa powder instead of 2 cups flour. Fold 1 cup whole skinned toasted hazelnuts into the dough. Chill, slice, and bake for 12 to 15 minutes, or until the cookies are firm and have a dull rather than shiny appearance.
Dried Apricot and Candied-Almond Sables
Follow the recipe for Vanilla Sables, but use only 1/2 cup superfine sugar. Gently knead 1/2 cup crushed praline and 1 cup diced dried apricots into the dough before chilling, slicing, and baking.
Follow the recipe for Vanilla Sables, adding the grated zest of 2 oranges with the egg and substituting 1 tablespoon Grand Marnier and 1 teaspoon pure orange extract for the vanilla extract. Fold 1 cup skinned toasted pistachios into the dough before chilling, slicing, and baking.