In a large skillet, cook sausage until no longer pink; drain. In a bowl, combine soup, milk, onion, salt and pepper. In an ungreased 11x7x2 baking dish, layer half the potatoes, soup mixture and sausages. Repeat layers. Cover and bake at 350°F for 1 1/2 hours, or until the potatoes are tender. Uncover and sprinkle with cheese. Return to oven for 5 minutes or until cheese is melted. Yield 4-6 servings.