Preheat oven to 350 degrees F.
In a large saucepan with a tight-fitting lid, combine melted butter and zucchini. Cover and cook over low heat, stirring occasionally, until tender, about 5 to 7 minutes. Remove from heat, set aside and let zucchini cool before adding eggs to avoid them becoming scrambled. Beat eggs with milk; add bread crumbs, onion, Worcestershire sauce, hot pepper sauce, salt, pepper, and 2 tablespoons of the Parmesan. Mix well. Let zucchini cool. Combine mixture with zucchini, stirring until blended. Turn into a buttered 1 1/2 quart casserole. Sprinkle top with remaining Parmesan. Bake uncovered for 35 to 40 minutes. If the dish has been refrigerated, allow about 10 minutes longer baking time.