At its simplest, gratin dauphinoise is a dish of thinly sliced potatoes baked slowly with cream and the merest hint of garlic. Some recipes include cheese, but I disagree. The dish is perfect with roast spring lamb, though I have been known to eat it as it is with a green salad to mop my plate. The potatoes are generally the yellow waxy sort so the slices keep their shape, though some of us prefer the collapsing floury varieties. A shallow, earthenware dish is the traditional cookware used.
Peel and thinly slice 1kg of waxy potatoes. Halve a juicy clove of garlic and rub it round the inside of a shallow baking dish, rub the dish with a little butter then put in the layers of potatoes, seasoning with salt and pepper as you go. Pour over 600ml of scalded double cream. Bake for about an hour and a half at 160C/gas mark 3.
Restraint with the garlic will be rewarded. The dish needs just a faint whiff of the bulb, and wiping the base and sides before adding the potatoes produces something more authentic than adding it crushed or sliced. Don't skimp on the cream as the top layer of potatoes will dry out. Most importantly, don't cut the potatoes too thickly. That way they take forever to cook and the cream will evaporate long before the potatoes are tender. The dish needs long, slow cooking.
There are many variations, some of which include grated Gruyère or Parmesan, dried porcini, anchovies and even eggs. I tuck pieces of smoked mackerel in mine if I am making it more of a main course, or pancetta. Incidentally, those perfectly round mounds of "dauph" you get so often in Parisian restaurants nowadays are straight from the freezer aisle at the cash and carry.