Rough Puff Pastry (recipe follows)2 large egg yolks (37 grams)3 tablespoons (45 grams) water, dividedApple Filling (recipe follows)2 tablespoons (24 grams) granulated sugar
Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
On a lightly floured surface, roll Rough Puff Pastry into a 21×13-inch rectangle (about ⅛ inch thick). Using a 4-inch fluted round cutter, cut out 15 circles, making sure to cut closely to previous cut. Discard scraps. Gently roll and stretch circles into 5½×4-inch ovals. Place on prepared pan. (Cover first layer with parchment paper, and stack a second layer on top; no need to use a second pan.) Freeze until dough is firm, about 5 minutes.
In a small bowl, whisk together egg yolks and 1 tablespoon (15 grams) water. Brush ovals with egg wash. Divide Apple Filling (about 1 tablespoon or 19 grams each) among pastry ovals. Fold ovals in half, creating a pocket, gently pressing together edges to seal. Return to pan. Brush tops with egg wash, and freeze until egg wash is set, about 5 minutes. Brush with egg wash again; freeze for 5 minutes more.
In a small microwave-safe bowl, heat sugar and remaining 2 tablespoons (30 grams) water on high until sugar dissolves, about 30 seconds, stirring as needed.
Line a baking sheet with parchment paper. Place half of pastries on prepared pan; return remaining pan of pastries to freezer. Using a small sharp knife, gently score desired design into top of pastries. Using a wooden pick, poke 4 to 5 holes discreetly in design to vent.
Bake until pastry is puffed and golden brown, about 20 minutes, rotating pan halfway through baking. Brush with simple syrup, and bake until deep golden brown and top of pastry looks dry and shiny, 1 to 3 minutes more. Let cool on pan on a wire rack for at least 15 minutes. Repeat with remaining pastries. Serve warm or at room temperature. Best served same day.