Make the pie crust:
In a large bowl, mix flour, salt, and sugar. Add cold butter and rub with your fingers or a pastry cutter until the mixture resembles coarse crumbs. Gradually add ice water, 1 tbsp at a time, until the dough comes together. Divide into 2 disks, wrap in plastic, and chill for at least 30 minutes.

Preheat the oven:
Preheat to 200°C (400°F).

Prepare the filling:
In a bowl, combine sliced apples, sugar, flour, cinnamon, nutmeg, and lemon juice. Mix well and set aside.

Assemble the pie:
Roll out one disk of dough and line a 23cm (9-inch) pie dish. Fill with apple mixture and dot with butter. Roll out the second dough disk and place over the filling. Trim and crimp the edges. Cut a few slits in the top crust to allow steam to escape. Brush with beaten egg and sprinkle with sugar.

Bake:
Place the pie on the lower oven rack and bake for 45–50 minutes, or until the crust is golden and the filling is bubbling. If the edges brown too quickly, cover them with foil.

Cool and serve:
Let the pie cool for at least 30 minutes before slicing. Serve warm with vanilla ice cream or whipped cream.

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