Spray each sheet of foil with cooking spray. Top each piece with equal portions of potatoes, bacon, onion soup mix, onion, and cheese and mix. Add salt and pepper to taste. Add 1 tablespoon of butter to each serving. Wrap securely.
Grill for 20 to 30 minutes. Or you can bake it in the oven, at 350° for about 35 minutes or till done. Let stand 10 minutes before serving. Serve in foil, topped with sour cream if desired.