In a skillet, saute onion in butter until tender. In a large bowl, combine the ham, chicken, peppers, olives, soup, sour cream, salt, pepper and onion. Fold in noodles.
Pour into a greased 2-1/2-qt. baking dish. Sprinkle with the Parmesan cheese. Bake, uncovered, at 325 degrees F for 45 minutes or until bubbly.