My mum used to make a potato dish called Potato Dauphinoise, a rich, luxurious dish with cream, garlic and sometimes cheese all layered together and baked until soft and creamy. It was a treat and usually confined to special occasions. I once made a version with both sweet potato and regular potatoes from a recipe in a Thanksgiving issue of Gourmet magazine. Cave aged Gruyere was used to help glue the layers together and create a cheesy sauce that was heaven, but only to be consumed in meagre portions.