Pre heat oven to 450°F

In saucepan, combine chicken, carrots, peas and celery. Add water to cover and boil for 15 min. Remove from heat, drain, and set aside

In same sauce pan, over medium heat, cook onion in butter until soft. Stir in flour, salt, pepper and celery seed.

Slowly stir in chicken broth and milk. Simmer over medium-low heat, stirring frequently, until thick. Remove from heat and set aside.

Place one pie crust in bottom if 9x9 pie plate. Add filling to pie plate

Cover with 2nd pie crust and make several slits in top crust

Bake pie on baking sheet for 30 to 35 min, or until pastry is golden and filling is bubbly.