Preheat oven to 375. Mix potatoes and sausage in a 9x13 greased baking dish. Mix soup, milk, salt and pepper, pour over potato mixture and stir. Cover with foil. Bake for approximately 60 minutes or until potatoes are done. If sauce is too thin, remove foil the last 20 minutes to thicken. Sprinkle cheese over casserole the last five minutes of baking.