Home-made, straight from the oven, it is truly one of the great classics.
I know it does seem extravagant to use 5 fl oz (150 ml) cream for 1 lb (450 g) potatoes, but I would forego a pudding with cream once in a while in order to justify it. And although cheese is sometimes added to this, I think it masks the potato flavour too much.
This recipe is taken from Delia Smith's Complete Cookery Course and Delia Smith's Complete Illustrated Cookery Course. Serves 3-4
First, peel the potatoes and slice them very, very thinly (a wooden mandolin is excellent for this operation, if you have one), then plunge the potato slices into a bowl of cold water and swill them round and round to get rid of some of the starch.
Now dry them very thoroughly in a clean tea cloth. Then in the gratin dish arrange a layer of potato slices, a sprinkling of crushed garlic, pepper and salt and then another layer of potatoes and seasoning. Now mix the cream and milk together, pour it over the potatoes, sprinkle with a little freshly grated nutmeg, then add the butter in flecks over the surface and bake on the highest shelf in the oven for 1½ hours.