Halve zucchini lengthwise. Scoop out pulp, leaving 1/4 inch shell. Chop pulp to make 1 cup set aside. Steam zucchini shells, cut side down for 5 to 6 minutes or until tender. In medium skillet, cook zucchini pulp and tomato in butter until squash in tender (about 3 minutes). Add eggs, salt and pepper to pulp. Cook over low heat until set. Spoon egg mixture into zucchini halves. Top with cheese. Heat until cheese melts- approx 3-5 min.