Preheat the oven to 350°F. Cook the bacon in a large oven-proof skillet over medium-high heat until crisp, about 5 minutes. Remove from the skillet to paper towels with a slotted spoon, reserving the drippings in the skillet.
Add the onion to the drippings and cook until tender, about 5 minutes.
Whisk together the bbq sauce, brown sugar, tomato paste, Worcestershire, vinegar, cornstarch, mustard, salt, pepper, and 1 cup water in a medium bowl.
Add the beans, sauce, and bacon to the onion. Bake, uncovered, for 30 minutes or until the beans are bubbly and the sauce is thickened.