Separate the sheets of puff pastry and thaw.
Peel the apples and cut into 1 cm (approximately 1/3 inch) wide slices. Meanwhile, coat a pan with butter. Add the sugar and cook until a light caramel, stirring constantly. Remove the pan from the heat and toss the apples in it. Place the thawed puff pastry on each other and roll out on a floured surface. Cut to the size of the pan and place over the apples. push down in the sides of the pan.
Bake the tart in a preheated oven at 225°C (approximately 440°F) for about 25 minutes. When it is crisp and brown, remove from the oven.
Immediately after the tart comes out of the oven, take a large plate and cover the pan. Quickly turn over the pan and turn out the tart. Be careful, it will be very hot. Serve immediately.