Prep: 25 min
Chilling time: 5 hours, 20 min
Total time: 6 hours, 15 minutes
Makes: 35-40 cookies
3/4 cup unsalted butter, cubed
1 cup granulated sugar
1 large egg
1 tsp vanilla
2 1/2 cups all-purpose flour
1/2 tsp baking powder
1/8 tsp salt
Blue food colouring
1/2 cup decorating sugar
In large bowl, beat together butter and sugar until fluffy. Beat in egg and vanilla until just incorporated, scraping down sides as needed. In medium bowl, whisk together flour, baking powder, and salt; stir into butter mixture until just incorporated.
Divide dough into two discs, reserving one half to a bowl and gently mix in a few drops of blue food colouring until incorporated. Wrap in plastic wrap, and chill for 1 hour. Allow to come to room temperature for 10-15 minutes before rolling.
Between two sheets of plastic wrap, roll blue dough into 12×8-inch rectangle; set aside. Repeat with pale dough. Set pale dough on top of blue dough and, starting at long edge, tightly roll up dough, pinching seams to seal. Wrap in plastic wrap and chill for 4 hours or overnight.
Sprinkle clean work surface with decorating sugar; unwrap dough log and roll in sugar until coated. Slice log crosswise into 1⁄4 inch slices. Arrange cookies 2 inch apart on large, parchment paper-lined baking sheets. Refrigerate until firm, about 20 minutes. Meanwhile, preheat oven to 350°F. When cookies are done chilling, bake, rotating pans halfway through, until edges are golden, 10-12 minutes.
Originally published in the Winter 2018 issue. Photo by Alanna Lipson.