Preheat oven to 200 degrees F. In a large skillet, heat 1 tablespoon olive oil over medium-high heat. Add half of the peameal bacon slices and cook for 3 minutes or until browned on each side, turning once. Remove from skillet. Repeat with remaining bacon slices, adding more oil as necessary. Return all bacon to the skillet.
In a small bowl, combine maple syrup and lemon juice. Add to skillet. Bring to boiling; reduce heat. Boil gently for 3 minutes or until liquid has nearly evaporated and bacon slices are glazed. Remove from heat and set aside.
Spread butter on one side of each bread slice. Turn slices over; spread with mustard. Top half of the slices with a slice of cheese; top cheese slices with a slice of bacon. Add remaining bread slices, buttered-sides up.
Heat a griddle or another large skillet over medium heat. Add half of the sandwiches. Cook for 3 to 4 minutes or until toasted and cheese starts to melt, turning once. Remove sandwiches to a baking sheet. Keep warm in oven. Repeat with remaining sandwiches. Serve warm.