Place chopped onions and sliced squash in a 2-quart, heat-resistant, non-metallic casserole with water.
Cover tightly and heat on full power 7 minutes or until squash is tender.
Drain excess water.
Soak crumbled slices of white bread in 1 cup milk for 5 minutes.
Add salt, monosodium glutamate, melted butter and grated cheese to bread and milk mixture.
Stir to combine.
Pour bread and cheese mixture over squash and stir to mix together thoroughly.
Sprinkle top of mixture with Italian flavored dry bread crumbs.
Cook, uncovered, on roast for 12 minutes or until cheese is melted.
Thermometer should register 160Â°F.