To make the pastry, place the flour, sugar and butter into a food processor and process it until it resembles fine breadcrumbs.
Slowly add the iced water and mix until a smooth dough forms. Knead the dough into a ball on a lightly floured surface.
Wrap in plastic wrap and place it into the fridge for a minimum of 30 minutes. If using store-bought pastry sheets, place them onto the bench to defrost. Preheat oven to 190 degrees celsius (180 if using fan forced). Grease a 24cm pie dish and set aside.
Meanwhile, place the apples and water into a saucepan over medium high. Stir occasionally for 5 minutes or until the apple has just started to soften.
Mix through the sugar, lemon juice and cinnamon.
Divide dough into 2 portions (one ⅔ for the base and one ⅓ for the top) and then roll out each portion until 3-5mm thick.
Place the larger piece of pastry over the pie dish and press down so that it covers the base and sides. Trim any excess.
Drain any excess liquid from the apple mixture. Add the apple mixture to the pie dish and spread out evenly.
Place the smaller piece of pastry over the apples, and crimp the edges lightly with your fingertips to seal around the rim of the dish.
Brush the lightly beaten egg over the top of the pie. Sprinkle over the raw sugar (optional).
Cut a 3-4 slits into the top of the pastry.
Bake in the oven for 30-40 minutes or until the pie pastry is lightly golden and crispy.