Insert the dough blade into the bowl of the food processor. Add the flour, butter, salt and nutmeg and pulse until the mixture has formed something resembling rough breadcrumbs. Add the yoghurt and switch to speed 1 until the mixture has formed a dough - about 20 seconds.
Halve the dough and roll out to about 4mm thick.
Line the bottom of a 22 cm pie dish and trim the edges to fit.
Whisk the cinnamon into the sugar or or place in a jar and give a good shake.
Layer in the apples and all but 1 tbsp of the sugar. It's best to mound them up higher than the dish as they will sink when cooking.
Roll out the remaining pastry to about 4mm thick and cover the top of the pie.
Trim the edges and crimp the sides or use a fork to press the pastry together. You can also use some of the pastry scraps to create some decorations to go on top.
Sprinkle the remaining sugar over the top and slash the pastry in order for some of the steam to escape.
Bake in the middle of a preheated oven at 200℃ (400℉, Gas 6) for about 30 minutes or until the pastry is golden and the apples are soft.
Serve hot or cold with clotted cream or custard.
Any remaining pastry will keep in the fridge for a couple of days or it can be frozen.Please note: calories and other nutritional information are per serving. They're approximate and will depend on exact ingredients used.