Divide the pastry into two, making one piece larger than the other (say, ⅓ and ⅔'s). Lightly dust the bench with some flour and place the larger piece of pastry on the bench. Lightly dust your rolling pin and roll out the pastry into a circle just larger than the pie dish.
Gently roll the pastry back over the rolling pin and transfer it to the pie dish. Gently push the pastry into the base and sides of the dish, then prick the base lightly with a fork. Place the pastry in the fridge for 15 mins to rest.
While the base is resting, roll out the smaller piece of pastry into a circle. Using either a knife, pizza cutter or fluted pastry cutter to cut strips of pastry about 2 cm wide.
Bring the pastry-lined pie dish out of the fridge and add the apple filling. Arrange the pastry strips on top of the apple, carefully weaving it over and under to create a lattice pattern. Press the edges to seal and trim the excess.
Brush with lightly beaten egg and sprinkle with raw sugar. Bake for 40-45 minutes or until golden and crisp and the apple filling is tender. Remove to a wire rack to cool slightly. Serve the apple pie warm dusted with icing sugar and a jug of homemade custard on the side.