Pink Grapefruit Sandwich Cookies

Preheat oven to 350 degrees. Line a baking sheet with parchment paper; set aside. In a small bowl, combine zest with 1 tablespoon sugar; set aside. In a medium bowl, whisk together both flours, baking powder, and salt; set aside.

In the bowl of an electric mixer fitted with the paddle attachment, beat butter and remaining sugar on medium-high speed until light and fluffy, about 2 minutes, scraping down sides of bowl as needed. Add egg yolks, and beat until combined, scraping down sides of bowl as needed. Beat in reserved zest-sugar mixture. Add flour mixture in two batches, alternating with the juice, and beat to combine.

Turn out dough onto a piece of plastic wrap, and shape into a 1-inch-thick disk. Wrap in plastic, and refrigerate until firm, about 30 minutes.

On a lightly floured work surface, roll out disk to 1/8 inch thick using a lightly floured rolling pin. Using a lightly floured 2-inch round cookie cutter, cut out rounds and place about 1 inch apart on prepared sheet. Bake, rotating sheet halfway through, until edges are golden, 18 to 20 minutes. Transfer sheet to a wire rack to cool 5 minutes. Transfer parchment paper and cookies to rack to cool completely.

Using an offset spatula, spread 1 tablespoon filling onto flat sides of half the cookies. Sandwich with remaining cookies, keeping flat sides down. Once filled, cookies can be kept in an airtight container in the refrigerator for up to 3 days.