Start by placing the rectangular sheet of puff pastry on your oven rack.
Then, arrange this pastry sheet by fitting it between the gaps in the oven rack and set aside.
Peel all the apples, cut them in half, remove their core and cut them into thin strips.
Fit these apple strips into the gaps left in the puff pastry.
To prevent the apples from turning brown, as soon as you cut them, always add some lemon juice.
Add granulated sugar on top of all the apples and pastry.
Moisten the ends of the pastry with some water, add another 300g sheet of puff pastry on top of everything and press the ends.
Then, sprinkle 2 more tablespoons of sugar over this pastry and sprinkle cinnamon powder to taste.
Take it to a preheated oven at 180° C (350° F) and bake for 35 minutes.
Serve.