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