Cook 4 slices bacon until crisp; drain, reserving 2 tablespoons drippings. Crumble bacon. Cook 1/2 cup chopped onion in drippings until tender; add with bacon to 2 (1 lb.) cans pork 'n beans in tomato sauce, 2 tablespoons brown sugar, 1 tablespoon Worcestershire sauce and 1 teaspoon prepared mustard. Mix well. Bake, uncovered in 1 1/2 quart casserole at 325 degrees for 1 1/2 to 1 3/4 hours. Makes 6 servings.