Prepare the Apples – Peel, core, and slice the apples thinly. Toss them with sugar and cinnamon.
Roll Out the Puff Pastry – Unroll the puff pastry and cut it into even rectangles or strips.
Assemble the Slices – Place apple slices on half of the pastry pieces, then cover with another pastry layer. Press the edges together with a fork to seal.
Brush & Bake – Brush the tops with whisked egg and bake in a preheated oven at 375°F (190°C) for 20–25 minutes, or until golden brown.
Garnish & Serve – Let cool slightly, then dust with powdered sugar or drizzle with caramel sauce.