For the crust:

1. In a large mixing bowl, mix together all-purpose flour and salt. Add the diced butter and press with your finger tips until you get a crumbly texture. Sprinkle sugar over and stir well. Add water, one tablespoon at a time, just enough to shape into a a smooth ball. Flatten lightly with your hand, wrap in cling film and place in the refrigerator for about 30 minutes.

For the apple filling:

1. Preheat the oven to 350°C (180°C) and grease a heavy cast-iron skillet. Set aside.
2. Peel, core and cut the apples into quarters. Place in a shallow dish and press the lemon juice all over to prevent the apples from browning.
3. Meanwhile, pour the sugar to the bottom of the skillet and let gently dissolve over a medium to low heat. Do not stir the pan but just shake the pan until dissolved. Heat until it becomes golden brown. When the caramel is ready, add the butter and cook a few of more minutes. Add the calvados when it starts foaming and cook for 2 minutes.
4. Arrange the apple quarters so they make a pretty pattern, remembering you will be inverting the tart, and cook for 10 minutes over a low heat.
5. Meanwhile, roll out the dough in a large disk, about 10-inch (25 cm) in diameter, and carefully top apples with the dough, tucking the edges in using two spoons. Prick with a small sharp knife. Put straight in the oven and bake for 25-35 minutes until the pastry is golden.
6. Remove from the oven and leave to cool for 5 minutes before placing a plate, slightly larger than the pan, on top of the pastry and very carefully, preferable using oven gloves, invert the tart onto the plate. Serve lukewarm, with a side of whipped cream or vanilla ice cream.