Place potatoes on a large microwave-safe plate (choose potatoes that are roughly the same size) and cook on high for 3-4 minutes (very little potatoes for 3 minutes, little potatoes for 4 minutes) until somewhat tender.
Preheat the grill to medium heat (about 350 degrees F).
Let cool enough to touch and slice potatoes thinly.
Lay two large sheets of aluminum foil together (or use a cast iron skillet or grill pan) and spray with cooking spray.
Place one single layer of potatoes on top. Combine salt and pepper and sprinkle ⅓ over potatoes. Top with ⅓ cheese and ⅓ bacon.
Repeat layers two more times until all potatoes, cheese and bacon are used. Fold up the sides (if using a skillet or pan, you may want to cover with foil to keep the heat in) and pinch the top closed. Place directly on heat, cover grill and cook for 10-20 minutes, until potatoes are tender all the way through. Open foil and sprinkle with green onions. Serve immediately.
*These potatoes can also be baked in the oven for roughly the same amount of time at 350-400 degrees F.