Slice potatoes onto a large sheet of heavy foil.
Sprinkle with a little salt, pepper, and the bacon.
Add onion and cheese cubes.
Dot butter over all.
Mix on the foil.
Bring edges of foil up, leaving space for expansion of steam.
Seal well with a double fold.
Place package on grill and cook over slow coals till done, about 1 hour.
Turn several times.