Lightly oil a 1 litre (1¾ pint) baking dish with spray oil. Peel the potatoes, then cut into wafer-thin slices. Arrange the slices, in overlapping layers, in the prepared dish, seasoning each layer with nutmeg, salt and pepper and adding small knobs of butter.
Mix the milk and cream together, pour over the potatoes and cover the dish with foil. Bake in a preheated oven, 190°C (375°F), Gas Mark 5, for 1 hour until the potatoes are almost tender.
Meanwhile, combine the breadcrumbs, pine nuts, Parmesan and parsley in a bowl.
Remove the foil from the gratin and scatter the breadcrumb mixture over to form a crust. Bake for a further 25–30 minutes until the topping is crisp and golden.