A remarkably quick & easy version if you want a slightly different (and tasty) way to serve potatoes.
Put thinly-sliced potatoes into a baking dish that can go on the stove top as well as in the oven. Add a layer of thinly-sliced red onion, garlic, salt and pepper, and grated Parmesan. Pour on a good slosh of cream and some water. Stir everything together, bring to the boil on the stove top, cover, and cook for 5 or 6 minutes.
Sprinkle on another generous handful of grated Parmesan and put in the oven, uncovered, for about 1/2 hour. It should be brown and bubbling. If necessary, brown it off under the grill
