Simmer the ketchup, vinegar, molasses, Worcestershire sauce, smoked paprika and garlic powder in a small saucepan for 5 minutes until glossy.
Cook the bacon in a heavy skillet over medium heat for 8 to 10 minutes until crisp, then drain it and wipe out all but a thin film of fat.
Shape the beef into 4 patties, dimple the centers and season both sides with the salt and pepper.
Heat the skillet over medium-high heat and sear the patties for 4 minutes without moving them.
Flip, brush each patty with 1 tablespoon barbecue sauce and cook for 4 to 5 minutes until the centers reach 160°F.
Add cheddar for the final minute and cover until melted, then toast the buns briefly in the cleared skillet.
Build each bun with one glazed cheeseburger patty, 2 bacon slices, red onion and another spoonful of barbecue sauce.