Butter a 9x13 baking dish. Cover bottom of dish with a layer of bread slices. Mix ham and cheese together and spread on top of bread. Cover with another layer of bread slices. Beat eggs, milk and salt together and pour over bread, ham and cheese. Cover and refridgerate overnight. In the morning melt butter and mix with Rice Crispies. Spread on top of casserole and bake uncovered for one hour at 350 degrees. Let rest 15 minutes before serving. You can use whatever type of cheese you like best. I usually use Kraft Classic Melts blend.