I have to make a large portion of this for a Christmas party. I'm thinking I want to go all out and make Gratin Dauphinoise the French way with just potatoes, heavy cream , cheese, garlic and butter, rather than making a mornay sauce with milk and a roux. I plan on cutting russet potatoes 1/8-1/4" on a mandolin slicer, then combining them in a saucepan with the cream and cheese and finally pouring that mixture into a large and deep hotel pan to finish in the oven. I would like to bake them in a disposable foil hotel pan (so we can leave early) but I'm concerned about poor heat transfer and possible burning. I could use a larger baking pan to create a water bath for the foil pan. Is this a good idea? Also, is there an easier (less messy) preparation I could do? Could I add the uncooked sliced potatoes to the hotel pan and just layer with grated cheese, cream and dot with butter? I'm also concerned about the whole thing separating and making an oily, grainy mess. I've had this happen on occasion but don't know why. Thanks for your advice!