Cover and cook squash and onions in a small amount of boiling water in a l arge saucepan, 5 minutes or until tender; drain well. Stir together squash and onion mixture, cheese spread and next 4 ingredients until blended; spoon into a lightly greased 13x9 inch-baking dish. Combine breadcrumbs and butter; sprin kle over squash. Bake at 300 degrees F For 55 min. or until golden brown.