First, preheat oven to 400° Fahrenheit. In a large saucepan place the broth, celery, potatoes, carrots, onions, and peas. Bring to a boil, reduce heat to a simmer, and simmer for 10 minutes.
Next, add chicken, and simmer 10 more minutes. Take out pie crusts from the fridge and roll out one to fit in the bottom of your pie pan.
Melt butter in a small saucepan. Stir in the flour and cook until it’s a delicious, golden roux. Allow it to boil for a few seconds, then add the milk, nutmeg, dried sage, dried thyme, salt, and pepper. Simmer for a few minutes, stirring constantly until a paste forms. Pour into the other saucepan.
Pour mixture into the prepared pie pan. Unroll the top crust and place over the mixture. Fold the top crust behind the top of the bottom crust and press gently. Then press edges down with the tines of a fork to seal. Cut vents or shapes near the center of the pie with a knife or use a fork to make holes.
Place on middle rack of oven. Bake for 35 to 45 minutes until crust is golden and filling is bubbling.