Mix the flour and salt in a bowl. Add the water and butter, combine quickly to form a soft dough. Flatten the dough, wrap in cling film, chill for approx. 30 mins.
To laminate the dough
Coarsely grate the cold butter, chill. On a lightly floured surface, roll the dough out into a rectangle (approx. 25 x 40 cm). Spread the cold, grated butter over two thirds of the dough, leaving a border of approx. 1 cm on three sides. Fold the exposed dough over the top, place the folded dough over the remaining dough. Press the edges down firmly, cover and chill for approx. 30 mins.
On a lightly floured surface, roll out the dough into a rectangle again (approx. 25 x 40 cm), then fold up one third of the dough and fold the remaining third over the top. Repeat this process two more times. Wrap the dough in cling film and chill for approx. 30 mins.
Peel and core the apples, cut into approx. 1 cm pieces. Place 300 g of the chopped apples in a pan with the sugar and lemon juice. Cover and simmer for approx. 5 mins. until soft. Remove the pan from the heat, mix in the remaining apples together with the cornflour, nutmeg and cinnamon.
Divide the dough into 3 equal portions. Combine two portions, roll out into a square approx. 4 mm thick, place in the pie tin and allow for a rim of approx. 3 cm, prick the base firmly with a fork. Spread the filling on top. Roll out the remainder of the dough into a square approx. 4 mm thick, place on top as a lid, press the edges down firmly, sprinkle with sugar.
Approx. 30 mins. in the lower half of an oven preheated to 200°C. Remove from the oven, loosen the tin frame, slide the pie onto a cooling rack and leave to cool.