• 1 sheet frozen puff pastry (from a 17.3 ounce package), preferably Dufour, thawed
• All-purpose flour, for surface
• 1 large egg, lightly beaten, for egg wash
• 1/2 cup fresh or good-quality applesauce
• 3 Granny Smith apples, peeled, cored, and cut into thin wedges
• 1 ounce (2 tablespoons) unsalted butter, melted
• 2 tablespoons sanding sugar, for sprinkling
• 2 tablespoons apricot preserves
• 1 tablespoon water