Boil chicken breast until tender. Sit aside to cool. Pour package of noodles into remaining liquid and boil until tender, may be necessary to add extra water. Once noodles are tender, drain water completely.
Chop onion, pepper and celery into small pieces. Saute in butter in large skillet.
Cube Velvetta into small pieces.
Once chicken has cooled cut or tear into small pieces.
Combine all ingredients into large corning ware dish, stir until mixed well. Cover with aluminum foil and bake at 400 degrees for 30 minutes.