Make the pastry by adding the cold butter into the flour and work through your fingers until it forms a crumb texture. Alternatively, use a food processor and pulse until a fine crumb stage. Gradually add the beaten egg and mix until the dough comes together. If needed, add the cold water to help bind the mixture. Wrap in cling film and place in the fridge to chill for half and hour.
Meanwhile, peel and slice the apples into a large bowl. Add the lemon juice, sugar and cinnamon and leave to sit while you roll out the pastry.
Remove the pastry from the fridge, divide in two and roll one piece out thinly on a floured work surface. Gentley place into a 9 inch pie dish ensuring it is fit into all the edges. Fill with the sliced apples and dot with butter. Roll out the second piece of pastry and lay over the top, sealing the edges of the pastry with water.
Using a sharp knife, trim the pastry from the sides and crimp to seal. Make a few slices on the top to allow steam to escape while baking.
Bake in a preheated oven at 220 C (fan 190 C) for 10 min. Lower the oven temperature to 190 C (fan 170 C) and continue to bake for a further 40-45 minutes. Remove from the oven and allow to cool slightly before cutting and serving.
You can save time by making the pastry the day before and removing from the fridge 30 minutes before rolling.Alternatively, there are some very good ready made shortcrust pastries in the supermarkets so feel free to use those too!