Heat the butter at low temperature in a frying pan with removable handle and add the sugar. Make a golden caramel. Peel the apples and brown them in the caramel. Place the puff pastry dish on the top and cover the apples. Put the frying pan in the oven and remove the handle. Bake for 20minutes at 180°C. Use the handle to remove the frying pan from the oven. Serve.