Tart tatin is one of the great classic desserts of French cooking. It's an apple tart cooked upside down. Apples are cooked in sugar until they caramelise. Then a circle of puff pastry is put on top, and the whole tart is baked at 356°F (180°C) for 20 minutes. To serve, the tart is turned over so that the apples are on top. Apples with caramel and crispy puff pastry taste amazing.