1 cup diced celery
1 cup diced onion
5 teaspoons seasoned dry mustard
1 teaspoon salt
1 teaspoon onion powder
1 teaspoon garlic powder
2 teaspoons dried minced onion
1 cup milk
1 teaspoon Worcestershire sauce
Preheat oven to 375 degrees F (190 degrees C).
In a medium stockpot, heat celery and onion over medium heat. Cook celery and onion until tender, about 15 minutes. Stir in mustard, salt, onion powder, garlic powder, onion, milk, Worcestershire sauce, chicken and celery mixture. Reduce heat to medium, cover and simmer 10 minutes.
Dredge chicken in flour and cornstarch. Add broth, chicken stock and celery mixture; stir. Reduce heat to medium-low. Pour the chicken mixture into baking dish.
Bake uncovered at 375 degrees F (190 degrees C) for 45 minutes, or until chicken is cooked through and juices run clear. Turn and bake for 5 to 8 minutes.
Remove chicken from oven and place in a saucepan. Add enough water to cover, but not too much to be clumped.
Remove skin from chicken, cut outside into strips and slice into 1 inch slices. Slice strips and place into a 9x13 inch dish. Remove strips, skin and lock halves in plastic bag. Pour celery mixture over chicken pieces. Brush celery mixture with egg whites. Chill in refrigerator.
Bake in preheated oven for 20 minutes, basting with cheese sauce every 5 minutes. Serve chicken immediately with celery mixture.