Preheat oven to 325 degrees. Arrange in alternate layers in buttered 11/2qt. casserole: 2 1/2 cups thinly sliced potatoes (sprinkle 1 Tbsp flour over each layer), 1/2 cup minced leeks, 1 cup lima beans, and 1 cup flaked cooked ham slices. Season layers with salt, pepper, and dry mustard. Then pour over the top: 2 to 21/2 cups hot milk (to just cover). Sprinkle with paprika. Cover and bake 1 hour or until potatoes are tender, removing cover last 1/2 hr.