Cook bacon till crisp. Remove bacon, reserving about 3 tablespoons drippings in skillet. Crumble bacon and set aside. Cook onion in reserved drippings till tender. Stir in pork and beans, brown sugar, catsup, worcestershire, and mustard.
Turn into 1 1/2-quart casserole. Bake, uncovered, at 350 for 1 1/2 - 1 3/4 hours. Stir; top with bacon. Let stand a few minutes before serving.