1 (2 1/2 inch diameter) celery heart
1 cup grated sharp Cheddar cheese
2 tablespoons finely chopped pimiento
3 pounds ground beef
1/2 cup quick-cooking rolled oats
1/2 cup evaporated milk
1 tablespoon seasoned salt
1 teaspoon garlic powder
1 teaspoon Worcestershire sauce
1/2 teaspoon chili powder
1/2 teaspoon pepper
2 eggs, slightly beaten
1/8 teaspoon liquid smoke
1/2 cup chopped scallions
1/4 cup chopped bell pepper
1 pound sliced bacon
Remove celery leaves and cut celery heart to about 8 or 9 inches long. Wash and dry. Keep bottom of celery heart intact. Do not remove root. Gently pull branches apart and sprinkle with salt. Combine cheese and pimiento; spread generously between celery branches. Wrap heart tightly in foil; chill while preparing meat loaf.
Combine all remaining ingredients except bacon, then mix. Turn meat mixture out onto large sheet of wax paper; pat out meat to an oval about 11 x 12 1/2 inches, Cut off bottom of root of celery heart. Place celery on center of meat; fold meat up and over celery. Pat into roll shape, completely enclosing celery. Lay bacon slices in chevron pattern over top of roll, making sure that slices overlap slightly. Gently roll onto one side and tuck bacon ends underneath. Use wooden picks to hold bacon ends in place, if necessary. Tie roll securely with string but not so tightly as to cut roll. Wrap in foil; seal top but do not close ends. Bake at 325 degrees F for about 1 hour and 30 minutes.
Yields 10 to 12 servings.