instruction: In a lightly greased 2 quart baking dish, layer onion and zucchini. Drizzle with 1/4 cup butter: sprinkle with mozzarella cheese. In a separate, combine remaining butter, bread crumbs and parmesan cheese. Sprinkle crumb mixture evenly over the top. Bake, uncovered, at 350 degrees for 35 - 40 minutes or until zucchini is tender.