Pour your beaten egg and cold water into the crumbly mixture. Stir quickly with a round-bladed knife until a soft dough forms. Wrap the dough in plastic wrap and chill it in the fridge.

Turn your oven to high heat now. Set it to 200C or 180C for fan ovens. Place a large flat baking tray inside to heat up early.

Peel, core, and slice your fresh cooking apples into clean pieces. Mix your golden caster sugar, cinnamon, and cornflour in a separate large bowl. Stir your apple slices into the sweet spice mixture until coated.

Roll out two-thirds of your chilled pastry on a floured surface. Press the flat pastry firmly into the bottom of your pie dish. Pile your spiced apple filling high inside the pastry-lined dish.

Roll out the remaining pastry to create a clean top lid. Brush the rim of the bottom pastry with a little egg wash. Place the pastry lid over the fruit and press tightly to seal.

Trim away any extra dough from the edges with a knife. Crimp the edges with your fingers to make a pretty pattern. Cut a few small holes in the center for steam to escape.

Brush the remaining beaten egg over the top of your pie. Sprinkle an extra tablespoon of sugar over the wet glaze. Bake in the oven for forty-five to fifty-five minutes until golden.