2Cook Canadian bacon in large frying pan over medium-low heat for 3 minutes on each side until hot. Leave in pan.
3Combine marmalade and mustard and pour over bacon in pan. Simmer 10 minutes, turning bacon often to coat in sauce.
4Place bread slices on ungreased baking sheet. Spread 1/2 tablespoon butter on top of each slice. Top with bacon slices. Spoon 1 teaspoon sauce over each slice of bacon, then top each with 2 slices of cheese.
5Broil sandwiches 3 inches from heat for 3 minutes, or until cheese melts.