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.
Source: Sunset Pasta Cookbook