1 stick butter
1 sm. chopped onion
1 (16 oz.) pkg. frozen broccoli, thawed
1 (16 oz.) pkg. cauliflower, thawed
1 can cream of mushroom soup
1 sm. jar Cheez Whiz
Ritz crackers

Mix all ingredients, except butter, in a 13"x9" baking dish. Melt butter and pour over mixture in dish. Crumble Ritz crackers and sprinkle over that. Bake 30 minutes at 350 degrees.