Build your sandwiches by dividing the ham between the rolls with 1 slice of cheese on each.
Place 2 sandwiches onto each piece of foil.
Whisk together the butter, mustard, onion and brown sugar. Pour evenly over the sandwiches.
Fold the sides of each packet up and seal closed.
Place on warm coals, turn frequent, and cook 10-15 minutes or until cheese is melted and bread is lightly toasted. (Cook on the grill on low heat or in the oven at 350°F for 15 - 20 moinutes.)
Notes
Store in foil in the refrigerator for up to 2 days; reheat at 350°F for 5-7 minutes.
Hawaiian rolls are ideal, but any soft dinner rolls will work.
Customize Fillings: Add mustard, mayonnaise, pickles, or veggies like spinach for extra flavor and variety.
Heavy-duty foil recommended, especially for grilling or campfire cooking.