Delia Smith's Gratin Dauphinois

Pre-heat the oven to gas mark 2, 300F (150C). First, peel the potatoes and slice them very, very thinly (a mandoline 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 whole nutmeg, then add the butter in flecks over the surface, and bake on the highest shelf in the pre-heated oven for 1½ hours.