Heat a cast-iron grill over medium heat. Slice the red onion about 1/4-inch thick, toss with EVOO, salt and pepper and place on grill until they are soft and are golden brown. When the onions are finished cooking, place the sliced Canadian bacon on the grill for about 2 minutes on each side or until golden brown, repeat with the Dole Pineapple slices about 3 minutes per side. After the onion, Canadian Bacon and pineapple are grilled to perfection, chop and toss together in a medium bowl.
To build the quesadilla, put down 1 layer of shredded cheese on one half of a tortilla, then a layer of Canadian bacon, pineapple-and-onion mixture then one more layer of cheese. Fold the tortilla in half and place on griddle, about 4 minutes on each side. Repeat with remaining tortillas.