In a large bowl, rub in the butter to the flour, icing sugar, and salt until it resembles breadcrumbs.
Bit by bit, add the water and mix until it starts to come together.
Turn out onto the bench and knead until you get a pliable dough.
Wrap in clingwrap and leave in the fridge for about 30 minutes.
When ready to roll out the dough, divide it in half. Roll one half out onto a floured surface until slightly larger than your pie plate. Transfer to pie plate and trim extra. You can pre-cook the bottom here so it doesn't go soggy with the filling, or leave it as is. To pre-cook, prick with a fork and pop in the oven for 10 minutes or so just until it is dry but not fully cooked. You can also add baking beads.
On the base of the pie, layer the apples, cinnamon and sugar with dots of butter throughout.
Roll out the pie top and transfer to the pie. Press down at the edges to ensure a good seal. Poke a hole in the top for the steam to escape.
Brush the top with beaten egg, milk, or cream, and sprinkle with a little granulated sugar.
Bake in a medium oven (about 180C) until filling is cooked through and the top is golden brown.