Combine water, celery seeds, & salt in large saucepan. Bring to boil over high heat. Reduce heat to medium-low. Add the chicken & cook until tender, about 20-25 minutes. Drain chicken, reserving 2 1/2 cups broth. Cool chicken until easily handled. Shred chicken.

Preheat oven to 350 degrees. Spray a 13x9 baking dish lightly with cooking spray.

Whisk eggs in a large bowl until blended. Add chicken, reserved broth, 1 1/2 cups cheddar, cream of chicken, cream of celery, stuffing mix, celery, & pepper. Mix well. Spoon chicken mixture into prepared baking dish.

Bake until browned & bubbly, about 45 minutes. Sprinkle with 1/2 cup cheddar. Bake until cheese nelts, about 5 minutes. Serve immediately.