Directions:

Barbecue Sauce:
Saute onion in olive oil in a saucepan over medium-high heat until tender. Reduce heat to medium. Add garlic; cook and stir for 1 minute. Stir in the ketchup, brown sugar, honey, chipotle peppers, apple cider vinegar, Worcestershire sauce and mustard.

Bring to a boil, stirring constantly. Reduce heat; simmer, uncovered, for 20 minutes, stirring frequently. Remove from the heat. Season with salt and pepper to taste.

Burgers:
Grease grill grate. Heat grill to medium.

Crumble beef over Worcestershire sauce in a bowl; mix just until combined. Divide beef mixture into eight portions; shape into balls. Form into patties, each about 1/4-inch thick. Place blue cheese in the center of four patties. Top with remaining patties; press meat edges to seal. Season with salt and pepper.

Grill burgers, covered, over medium heat for 5-8 minutes on each side or until a thermometer inserted into patties reads 160 degrees F.

Spread barbecue sauce on bun bottoms; top with burgers, barbecue sauce, lettuce and tomato. Replace bun tops.