These pretty spiral cookies are more than just colorful. Their flavor is reminiscent of fresh strawberries and cream, thanks to the addition of freeze-dried fruit and a dash of good vanilla.
To make the white dough: In a medium bowl, beat together the sugar, butter, salt, and vanilla. Add the flour and mix to form a cohesive dough. Divide the dough in half and place each half on a sheet of plastic; flatten the dough to a 5" x 7" rectangle, then wrap and chill for 2 to 4 hours.
To make the red dough: Place the confectioners’ sugar and freeze-dried strawberries in the bowl of a food processor. Process the mixture, pulsing occasionally, until powdered. Whisk the mixture through a mesh strainer to remove any chunks or stray seeds.
Add the butter, salt, and vanilla and mix until smooth. Add the flour and mix until evenly combined. Divide the dough in half and place each half on a sheet of plastic; flatten the dough to a 5" x 7" rectangle, then wrap and chill for 2 to 4 hours.
To shape: Place a sheet of parchment on your work surface and lightly dust it with flour. Unwrap one of the squares of white dough, place it on the parchment, and roll it into an 11" x 6" rectangle. Whisk together the glaze ingredients, then brush the glaze over the rectangle of dough and set aside.
On a separate piece of floured parchment, roll out one of the pieces of red dough to an 11" x 5" rectangle. Using the parchment to help you, flip the red dough over onto the white, lining up the sides and leaving 1/2" of white dough showing along the long edges. Peel off the top sheet of parchment.
Use the parchment to help roll up the dough into a tight log with no gaps, starting at the long edge. Wrap with the parchment and overwrap with plastic. Freeze the log for at least 1 hour. Repeat with the remaining two pieces of dough.
To bake: Preheat the oven to 350°F. Line three baking sheets with parchment.
Working with one log of dough at a time, remove from the freezer, unwrap, and use a pastry brush to gently coat the chilled log in egg wash.
Pour the sparkling sugar onto a piece of parchment, and roll the egg-washed dough in the sugar to coat.
Use a sharp knife to cut it into 1/4" to 3/8" slices. Give the log a quarter turn after each cut; this will help to keep it round. Transfer the cookies to the prepared baking sheets. Repeat with remaining logs of dough.
Bake for 12 to 14 minutes or until they feel firm. Remove from the oven and transfer to a rack to cool.
Storage information: When cool, store airtight at room temperature for up to a week; freeze for longer storage.
