Preheat oven to 375 degrees. Cook pasta according to package directions. Rinse with cold water, drain, divide into three portions and set aside.

Spread one third of pasta along bottom of large, deep glass or metal baking dish. Top with one cup shredded cheddar. Top with three slices American cheese. Scatter one third of margarine, cut in pieces over top. Repeat layers until dish is full, app. half inch from top, finishing with margarine. Set aside on baking sheet. Prepare sauce.

Whip eggs until fluffy. Slowly add evaporated milk, salt and pepper. Carefully pour sauce into casserole dish. Cover tightly with foil. Bake on cookie sheet (in case dish bubbles over), 35 minutes. Remove foil. Continue baking 15 minutes or until lightly browned and bubbling. Let rest 10 minutes before serving.