In a large saucepan on medium, melt the butter, and cook the onion&celery until soft.
Add broth, cream, and cream cheese, whisking the entire time until smooth.
Keep whisking, add the herbs, spices, and half the salt.
Taste, and add more salt as needed.
Reduce to low, lightly sprinkle the xanthan gum and keep whisking until the mixture thickens.
Adjust the thickness with adding more xathan gum, or cream.
Stir in the shredded chicken and the optional peas & carrots. (these need to be frozen or else they'll turn to mush).
Pour the mixture into the baked pie crust, cover with the top, press together.
Bake 25-30 minutes, until crust is golden brown. If the edges brown too quickly, cover the edge with foil or a pie shield after15 minutes.
Let cool for 5-10 minutes before serving.