Heat grill. Place onions in 9 1/4x6 1/2x1-inch disposable foil pan. Drizzle with melted butter; sprinkle with brown sugar. Cover loosely with foil.
When ready to grill, place foil pan on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 15 minutes. Uncover; stir onions and cook an additional 15 minutes or until onions are tender.
Dot onions with small spoonfuls of cheese spread; sprinkle with bread crumbs. Cook, uncovered, about 5 minutes or until cheese is melted.