Cut three pieces of aluminum foil and place two of them cross-ways on top of each other, shiny side up. Fold the edges of the bottom piece over the top piece and then fold the edges of the top piece over. Set aside.
Cut the potatoes into cubes and mix them with the onion and garlic. Place on the folded aluminum foil. Put each tablespoon of butter on top of potatoes, spaced out. Sprinkle with seasoning.
Fold in two sides of the aluminum foil over the potatoes, then roll the other two sides in. Take the third piece of aluminum foil and fold over the top.
Put in grill at 200 degrees for 1 hour. It's helpful to put them on right when the charcoal is lit and leave them in while you're getting the rest of your meal prepared, Matt will even leave them in and put whatever meat we're having in with them.
RIGHT when you take them off the grill, open up the foil and put the cheese on top to melt. TA-DA!!!!