Remove the onion skin. Cut the onions in half and slice each half of the onion into very thin slices. In a saute pan heat 3-4 tablespoons of butter until melted. Add the onions to the hot butter and saute on medium-high heat for several minutes until the onions begin to soften and turn brown and carmelized. When the onions are cooked, season them with a little Montreal Steak Seasoning (or salt and pepper) and remove from the heat. Heat a griddle pan to medium heat. Spray the griddle or add a little smear of butter to the pan if you want more flavor. On each piece of bread place one slice of Swiss cheese on one side and a slice of Provolone cheese on the other side. If you are adding pears, slice the pears thinly and place a couple slices of pears on one side of the bread. On top of the pears, add a good portion of the sauted onions. Put the sandwich together and place on the hot griddle to cook. Cook on both sides until the cheese is melted and the tops are golden brown and crusty. Remove from the heat and serve with fresh fruit as a side.