On a lightly floured surface, roll half of Rough Puff Pastry Dough into a 12-inch square. Sprinkle with 3 tablespoons (36 grams) turbinado sugar. Using a rolling pin, gently roll over sugar to press sugar into dough. Carefully turn dough over so sugar side faces down.
In a small bowl, stir together Berry Jam and cornstarch. Spread half of jam mixture onto dough. Roll up dough from two opposite sides, jelly roll style, meeting in center. Place log on its side on a baking sheet (coiled portions stacked to look similar to a capital “B”). Freeze until firm enough to slice, 15 to 30 minutes.
Repeat procedure with remaining dough, remaining turbinado sugar, and remaining jam mixture.
Preheat oven to 400°F (200°C). Line several baking sheets with parchment paper.
On a cutting board, place dough logs on their side. Using a serrated knife, cut dough into ½-inch-thick slices. Place slices, cut side up, 2 inches apart on prepared pans. Freeze until firm, 10 to 15 minutes.
Bake until bottoms are golden brown, 15 to 20 minutes. Let cool on pans for 5 minutes. Remove from pans, and let cool completely on wire racks. Store in an airtight container for up to 2 days.
Notes
Feel free to use your favorite flavor of store-bought jam in place of the Berry Jam.
Recipe by Bake from Scratch at https://bakefromscratch.com/berry-palmiers/