4 cups all-purpose flour 1/4 teaspoon salt 1 pound unsalted butter, at room temperature, cut into small pieces 1 cup granulated sugar 4 cage-free egg yolks 2 teaspoons vanilla extract About 1/4 cup crystal sugar
Using a sifter, or placing the ingredients together in a fine-meshed sieve and tapping its rim, sift together the flour and salt into a mixing bowl.
In the large bowl of an electric mixer, using the paddle attachment or beaters, or in a large mixing bowl using a hand-held electric mixer, beat together the butter and sugar until very creamy; start on low speed and, when the ingredients are combined, raise the speed to high and continue to beat until fluffy. On medium speed, beat in the egg yolks and then the vanilla. Add the flour mixture and beat just until combined. (The dough will clog the paddle or beaters, but it will be creamy).
Remove the dough from the bowl, gather into a ball, and wrap it in plastic wrap. Refrigerate until it firms up slightly; about 1 hour.
Remove the dough from the refrigerator and divide it in half. Roll each half into a log about 12 inches long and 2 inches in diameter. Wrap each log in plastic wrap and refrigerate for at least 2 to 3 hours or, preferably, overnight.
Place the oven rack in the top third of the oven. Preheat the oven to 350 degrees F. Line 1 or 2 baking sheets with parchment paper.
Working with 1 log at a time, cut the log into about 40 cookies, each about 1/4 inch thick. Arrange the cookies on the prepared baking sheet, about 2 inches apart, and sprinkle with crystal sugar. Bake until the edges of the cookies are golden brown, 10 to 11 minutes.
With a wide metal spatula, transfer the cookies from the baking sheet to a wire rack to cool. Repeat with the remaining log and crystal sugar. (If you’re using the same baking sheet, let it cool before putting another batch on it).
Store the cooled cookies in an airtight container at room temperature.