Preheat the oven to 400°F. Spray the baking dish with cooking spray.
Pour the beans into the baking dish. Add BBQ sauce, brown sugar, mustard, and Worcestershire. Stir to mix well.
Cook the bacon in a skillet until browned and crispy. Add the bacon and 3 tablespoons of drippings to the beans. Leave one tablespoon of bacon drippings in the pan. Add the onions and cook until wilted. Then add them to the beans and stir. Bake for 45 minutes or until the sauce thickens.