Layer the casserole ingredients. To your prepared baking pan, layer the 2 pounds of washed, peeled, and cubed russet potato pieces. Then, add 16 ounces of diced, cooked ham and pour the cheese sauce over them. Next, top with the remaining ½ cup of cheddar cheese and ¼ cup of mozzarella cheese. After layering all the ingredients, cover your baking dish with a sheet of aluminum foil.