1. Slice tomatoes into 1/2 inch slices. Combine crumbs, salt, pepper and 4 tablespoons of melted butter.
2. Sprinkle one third of crumb mixture into bottom of a greased 8x8x2 inch baking pan. Arrange half of tomato slices over crumbs. Sprinkle with half of minced onion. Sprinkle with another third of crumbs. Repeat.
3. Drizzle remaining melted butter and water over top of last crumb layer. Cover; bake at 425°F for 15 minutes. Uncover, and continue to bake until tomato slices are tender (about 15 more minutes). Sprinkle, if desired, with chopped parsley.