Line 2 baking sheets with parchment paper.
On a lightly floured surface, roll Yeasted Rough Puff Pastry into a 12x8½-inch rectangle (about ¼ inch thick). Cut rectangle in half lengthwise, creating 2 (12x4¼-inch) rectangles. Holding each short end of 1 rectangle, tightly twist in opposite directions twice, gently pulling to elongate into a tapered baguette shape. Gently pinch ends, and place on a prepared pan. Repeat with remaining dough rectangle. Cover loosely with plastic wrap, and let rise in a warm, draft-free place (75°F/24°C) until puffed, 1 to 1½ hours.
Preheat oven to 400°F (200°C).
In a small bowl, whisk together egg and 1 tablespoon (15 grams) water. Using a pastry brush, lightly brush egg wash onto 1 baguette. (Do not brush remaining loaf until ready to bake.)
Bake, one loaf at a time, until puffed and golden brown, 13 to 18 minutes. Let cool on pan on a wire rack for 15 minutes. Remove from pan, and let cool completely on a wire rack.