Crisp, thick-cut bacon strips are accompanied by sharp cheddar cheese and a homemade bacon jam that is perfectly sweet and smoky.
Coarsely chop the bacon. In large, heavy-bottom saucepan set over medium heat, cook bacon until crisp and fat is foamy. Using slotted spoon, transfer to paper towel-lined tray; set aside.
Drain off all but 2 tbsp bacon fat. Add 1 tbsp butter to saucepan; cook onion, garlic, rosemary, salt and pepper for about 10 minutes or until very soft but not browned. Stir in brown sugar and cider vinegar.
Add chopped bacon to the mixture and stir in apple juice. Simmer for 10 to 15 minutes or until mixture is deep caramel color and jam-like consistency. Remove from heat; stir in red wine vinegar and Worcestershire. Let cool completely. (Bacon jam can be tightly covered and refrigerated for up to 2 weeks.)
Cook remaining bacon until crisp. Drain on paper towel–lined plate. Spread remaining butter over one side of each slice of bread; lay two slices in nonstick skillet or flat grill pan, butter side down. Layer slice of Cheddar, 1/4 cup bacon jam, one-quarter of the crisp bacon strips and another slice of Cheddar over top of each one; cap with slice of bread, butter side up.
Cook over medium heat for 3 to 5 minutes per side or until bread is golden brown and cheese is melted (reduce heat and partially cover pan if bread browns faster than the cheese melts). Repeat with remaining bread, Cheddar, bacon jam and bacon strips. Let stand for 2 minutes. Cut in half and serve immediately.