From America's Test Kitchen Season 10: The Cookie Jar
During the holidays, these French butter cookies offer sophistication and style. That is, if you can capture their elusive sandy texture (sablé is French for sandy), which separates them from sturdy American butter cookies. Most of the sablé recipes we came across had only slight differences in ingredient proportions—but they all baked up without the delicate crumbliness that defines this cookie. To create the hallmark sandy texture of sablés—light, with an inviting granular quality similar to shortbread—we would have to do some detective work.
We started with a basic recipe using the typical method of creaming butter and sugar, then adding egg and flour. We then chilled, sliced, and baked the dough—but these cookies were missing the delicate crumbliness that defines sablés. We needed to decrease the liquid in the dough so there would be less moisture to dissolve the sugar particles. Cutting back on butter helped, as did the inclusion of a hard-cooked egg yolk, an addition we came across in our research. Adding the mashed yolk during creaming eliminated moisture and perfected the texture of the cookies. Brushing the cookies with a beaten egg white and sprinkling them with coarse sugar before baking added a delicate crunch and an attractive sparkle.
Makes about 40 cookies
Turbinado sugar is commonly sold as Sugar in the Raw. Demerara sugar, sanding sugar, or another coarse sugar can be substituted. Make sure the cookie dough is well chilled and firm so that it can be uniformly sliced. After the dough has been wrapped in parchment, it can be double-wrapped in plastic and frozen for up to 2 weeks.