Melt butter in large sautee pan. Cook onions 20 minutes until soft but not brown.

Add Zuchinni & cook covered for 10 minutes until tender.

Stir in flour and add hot milk. Cook over low heat for a few minutes until it makes a sauce. Pour into baking dish.

Combine bread crumbs and cheese. Sprinkle over mixture in baking dish. Top with diced bread and dot with butter.