Apple pie with crumble topping

Method

1. For the pastry, whizz the flour, sugar, a pinch of salt and the butter in a food processor until the mixture resembles coarse crumbs. With the motor running, pour in the egg and 1-2 tbsp water and whizz until a dough starts to form, adding a splash more water if needed. (Alternatively, in a mixing bowl, rub the butter into the dry ingredients with your fingers until the mixture resembles breadcrumbs. Add the egg and 1-2 tbsp water and mix with a round-bladed knife until a dough forms.) Flatten the dough into a disc, wrap in cling film and chill for 1 hour.
2. Heat the oven to 190°C/170°C fan/
gas 5. Roll out the dough on a lightly floured work surface until about 6-7cm larger than the circumference of the pie dish and about 4mm thick. Loosely roll the dough around the floured rolling pin, then roll over the pie dish, tucking it into the edges. Trim any overhanging pastry, crimp the edges using your fingers, then prick the base with a fork. Chill.
3. Put the apple, sugar, cinnamon and cornflour in a medium saucepan and toss together. Put the pan over a medium heat and cook for 10 minutes or until the apple slices are just soft.
4. For the topping, in a mixing bowl, rub the flour, sugar and nutmeg into the butter with your fingers until it has the texture of breadcrumbs 
with a few larger pieces. Chill while you bake the pie case.
5. Line the chilled pie case with 
non-stick baking paper, fill with baking beans or uncooked rice and bake for 25 minutes. Remove the baking beans/rice and bake for 
10-12 minutes more until the pastry case is golden and dry to the touch.
6. Tumble the cooked apples into the pie case, then scatter over the crumb topping. Bake for 25-30 minutes until golden and crisp on top. Serve with cream or vanilla ice cream.