Sparkling Shortbread Cookies

01Method

1. 1

   Using an electric mixer, cream the butter, both sugars, salt, and nutmeg together in a large bowl until pale and fluffy, about 2 to 3 minutes. Beat in the egg yolk, vanilla, and almond extract until fully combined. Add half the flour along with the cornstarch and mix until just incorporated, then fold in the remaining flour until a dough forms.

2. 2

   Gather the dough and press it into a compact ball with your hands. Transfer to a sheet of parchment paper and shape into a log approximately 11 inches long and 1½ inches in diameter, dusting your hands lightly with flour if the dough sticks. Roll the parchment around the log and twist both ends to seal. Refrigerate until firm, about 1 hour.

3. 3

   Combine the egg white and water in a small bowl and whisk until smooth.

4. 4

   Spread a long piece of plastic wrap flat on the countertop and pour the sanding sugar in a strip along the center.

5. 5

   Take the chilled dough log out of the refrigerator. Brush a thin, even coat of the egg white wash over the entire surface of the log. Lay the log onto the sanding sugar and roll it to pick up a full coating, pressing any stray sugar firmly onto bare patches. Wrap the coated log in the plastic wrap and return to the refrigerator for 30 minutes.

6. 6

   Heat the oven to 350°F (180°C) and line baking sheets with parchment paper.

7. 7

   Unwrap the chilled log and slice it into rounds just under ½ inch thick. Arrange the rounds about 1 inch apart on the prepared baking sheets.

8. 8

   Bake one pan at a time until the cookies appear set, 15 to 20 minutes. Let them rest on the pan for 5 minutes, then transfer to a wire rack to cool completely. Store any leftovers in an airtight container.