This classic French potato gratin dish is world famous, and rightly so! I am quite happy to have this as a main meal, with just some crusty bread and a large mixed salad on the side. I have heard that this famous dish was created as a way of encouraging the "Dauphin" (the young prince destined to become King Henri II), to eat up his vegetables, hence the name! Maybe - it is certainly just as popular with children, as it is with adults. Try to slice the potatoes as thinly as possible for the best results. A wonderful accompaniment for all sorts of roast meats, stews, casseroles and poultry. This recipe is not strictly French, using as it does a Swiss cheese.