Layer 1/3 of the potato slices in the buttered casserole dish. And of course these scalloped potatoes also have ham. Combine the two grated cheeses. Whisk in flour and black pepper until totally combined. Using a mandoline or slicer, slice potatoes into 1/8-inch slices (very thin.) (You may add salt, but cheese and ham are salty, so add sparingly.) You could say they are cousins – scalloped potatoes often have cheese added to the dish. Scalloped potatoes are very similar to au gratin potatoes. Set aside. Slice the potatoes. I used a mandolin to get perfect sliced potatoes. The potatoes should be thin and evenly sliced. Set aside.