Blueberry Jam Pinwheel Cookies
3 Cups flour
½ teaspoon baking powder
½ teaspoon salt
1 Cup unsalted butter, at room temperature
1 Cup Blueberry Sugar
1 large egg
2 teaspoons lemon zest
⅔ Cup Blueberry Jam
Turbinado sugar
Whisk together flour, baking powder, and salt in a large bowl. Beat butter and Blueberry Sugar with a mixer on medium-high speed until pale and fluffy. Beat in egg and lemon zest, then reduce speed to low. Add flour mixture and beat just until combined. Divide dough in half; wrap each portion in plastic and flatten slightly to form a disc. Chill in the refrigerator for one hour.
Roll one disc of dough out on a lightly floured board to a 10 x 12-inch rectangle (1/4-inch thick); trim edges if needed. Place preserves in a small bowl and microwave briefly (about 10 seconds); whisk to loosen. Use an offset spatula to spread 1/3 cup Blueberry Jam over dough, leaving a 1-inch border at the top and a 1/2-inch border at the sides. Roll dough up into a log; moisten edges and pinch to seal. Wrap roll in waxed paper and twist ends to secure, then chill for 24 hours (or freeze up to 1 month)*. Repeat with remaining dough.
Preheat oven to 350°F and line two baking sheets with parchment paper. Use a serrated knife to cut rolls into 1/4-inch slices, rotating rolls to keep them from flattening (reshape into rounds if needed). Place slices two inches apart on prepared baking sheets and sprinkle lightly with turbinado sugar. Bake, rotating pans halfway through, for 12 minutes, until edges are set. Cool for 1 minute on baking sheets, then transfer cookies to a wire rack to cool completely. Store in an airtight container at room temperature up to 2 days or freeze up to 3 months.
