For the pastry; combine flour and salt into a large bowl. Add diced butter and place in the freezer for 30 minutes.
Tip the mixture into a food processor, add iced water and pulse until the mixture resembles fine breadcrumbs.
Turn mixture out to a lightly floured bench and bring together with the heel of both hands until you have a smooth dough.
Divide into two pieces, shape into discs and cover both with plastic wrap. Place in the fridge to rest for at least 30 minutes.
On a lightly dusted work surface, roll your pastry until about 5mm thick and drape into a greased pie dish. Trim the edges and roll into a disc to be returned to the fridge with the lined tin for another 30 minutes.
Preheat oven to 200C.
Toss the apples, lemon juice and caster sugar together until well combined. Pile into chilled pie dish lined with pastry.
Roll out the remaining pastry for the lattice top. Cut into strips of varying lengths.
Lay 5 of these across the filled pie dish. Turn the pie dish around and take another piece of pastry and thread in and over the pastry strips already in place.
Repeat with remaining pastry. This sounds a bit tricky but honestly it's not hard once you get the general idea.
Whisk egg and cream together to make egg wash and brush over pastry.
Bake in oven 35 minutes or until golden. Serve warm with a dusting of icing sugar.