Checkerboard Shortbread Cookies

In the bowl of an electric mixer, using the paddle attachment, combine butter and sugar, blending on medium speed until well combined. On low speed add egg yolk and vanilla and blend well.

Slowly add flour. Mixture will be very crumbly. Remove the paddle and use your hands to combine mixture into a soft dough.

Divide the dough in half. Using any color you like, incorporate some food coloring into each half of the dough, kneading to incorporate the color completely.

On a lightly floured work surface, roll each piece of dough into a 5 ½ inch square approximately ¼ inch thick. It is important that both squares are exactly the same size.

Wrap each square in plastic wrap and place on a sheet pan. Chill in the refrigerator until firm; about 2 hours.

Unwrap one square and place on a work surface. Using a pastry brush, paint a little egg white over the entire surface. Place the second square of dough on top. Place a flat sheet pan or small cutting board on top of the stack of dough, pressingly down lightly so both squares adhere to each other.

Using a sharp knife, cut a ¼ inch thick slice of the layered dough and lay cut side down. Paint a little egg white onto the slice, and then place another slice on top of it, with the colors reversed to form a small checkerboard. This stack can be left as is to bake small cookies, or can be add to other slices to create a larger stack, and therefore larger cookies. Repeat slicing dough and stacking as you desire.

Chill each stack in the refrigerator on a sheet pan lined with waxed paper until almost firm. At this point, each stack could also be wrapped in plastic wrap and frozen to be baked at another time. They can be stored for up to three months.

When ready to bake, preheat the oven to 350 degrees Fahrenheit.

Remove stacks from refrigerator and on a cutting board, slice each stack ¼ inch thick. Place cookies onto a parchment-lined sheet pan 1 inch apart. Bake approximately 10 minutes, or until slightly puffed but not brown. Cookies will firm as they cool.