Servings: 6 Following package directions, cook rotini in a large kettle of boiling salted water until al dente. Drain, rinse with cold water, and drain again. Meanwhile, melt butter in a wide frying pan over medium-high heat. Remove sausage casings, crumble meat into pan, add onion, and cook until sausage is browned and onion is limp (about 5 minutes). Pour off drippings and add cooked pasta, chilies, milk, salt and pepper to taste. Pour half the mixture into a greased 2 1/2 quart casserole; sprinkle with half the cheese. Add remaining mixture, arrange tomato slices on top, and sprinkle with remaining cheese. If made ahead, cover and refrigerate until next day. Bake, uncovered, in a 350 deg F oven for 25 to 35 minutes or until top is slightly browned. Makes 6 servings.