Preheat the oven to 190C/375F/Gas 5.
Pinch off a quarter of the shortcrust pastry and set aside. Roll out the remaining pastry onto a lightly floured work surface to a 0.5cm/¼in thickness.
Carefully line a 23cm/9in springform cake tin with the rolled pastry, folding any excess pastry down the sides of the tin. Line the pastry case with baking parchment and fill with ceramic baking beans.
Transfer the pastry case to the oven and bake for 15 minutes. Remove the baking parchment and baking beans from the pastry case, then return the pastry case to the oven and continue to bake for a further 5-8 minutes, or until pale golden-brown. Remove from the oven and set aside to cool slightly. Trim off any excess pastry at this stage.
Sprinkle the semolina flour into the bottom of the pastry case (this will absorb any excess moisture.)
Meanwhile, boil the potatoes in a pan of salted water for 2-3 minutes. Reduce the heat until the water is simmering, then add the onions and simmer for a further 2-3 minutes, or until the potatoes and onions are just tender. Drain well.
Return the vegetables to the pan and add the double cream and flour. Season, to taste, with salt and freshly ground black pepper, then mix until the ingredients are well combined.
Arrange the apple slices in a layer at the bottom of the pastry case. Spoon over a third of the potato and onion mixture, then sprinkle over a third of the chopped sage and a third of the chopped ham and season, to taste, with salt, freshly ground black pepper and soft brown sugar. Repeat the process twice more.
When all of the filling ingredients have been used up, carefully pour over the cider, making sure that it does not fizz over the sides of the pie.
Roll the remaining pastry out onto a lightly floured work surface until the pastry is large enough in diameter to cover the top of the pie.
Brush the edges of the pastry case all over with a little beaten egg. Place the pastry crust on top, pinching the edges of the pastry together to seal. Using a sharp knife, cut a small cross in the centre of the pie crust to allow the steam to escape.
Transfer the pie to the oven and bake for one hour, or until the top of the pie is crisp and golden-brown and the filling mixture is bubbling. When the pie is cooked, remove it from the oven and set aside to cool before serving.
