From America's Test Kitchen: "The quickest way to slice the potatoes is in a food processor fitted with an 1/8-inch slicing blade. If the potatoes are too long to fit into the feed tube, halve them crosswise and put them in the feed tube cut-side down so that they sit on a flat surface. If the potato slices discolor as they sit, put them in a bowl and cover with the cream and chicken broth. If you like, use Parmesan instead of cheddar."