French Butter Cookies (Sablé Breton)
These are crisp, slightly-crumbly, and totally worth your time.
For the cookie dough:
- 10 tablespoons (140g) unsalted, good-quality butter at room temperature
- 1/2 cup (100g) sugar
- 1 large egg, at room temperature
- 1 teaspoon pure vanilla extract
- 2 cups (260g) all-purpose flour
- 1/2 teaspoon baking powder
- 1/2 teaspoon salt
For the egg wash:
- 1 room temperature egg beaten with up to 1 tablespoon heavy cream or half-and-half
Making the cookie dough:
Using the paddle attachment of a standing mixer, beat the butter and sugar at medium speed until light and fluffy -- 2-3 minutes. Add the egg and vanilla, and beat at low-medium speed until incorporated -- about 1 minute.
In a separate bowl, whisk together the flour, baking powder, and salt. Add the flour mixture to the butter mixture, and beat at lowest speed until incorporated -- about 1 minute.
Form the dough into a rough ball. Then wrap the dough in cling film and let it chill in the refrigerator for at least 30 minutes.
Rolling out the dough:
Cut the chilled dough in half. Roll each half between sheets of parchment paper until the dough is between 1/8- and 1/4-inch thick. Place the dough, still in its parchment paper sandwich, on a baking sheet. Refrigerate until the dough is cold and firm -- 30-40 minutes. Or, freeze the dough for 15-20 minutes.
Pressing out the cookies:
Preheat the oven to 350°F. Peel off the top sheet of parchment paper, and press out cookies with a fluted, 2-inch-diameter biscuit cutter. Transfer cookies to parchment- or silicon mat-lined baking sheets.
Brush the cookies with the egg wash. Then, using the tines of a fork or a toothpick or wooden skewer, make crosshatch markings on the top of each cookie.
Baking and storing the cookies:
Bake in the preheated oven until the cookies turn golden-brown around the edge, and the tops color lightly. Cool completely on a wire rack. Store the cookies in an air-tight container for up to 4 days. For longer storage, freeze the cookies.