Preheat oven to 425 degrees
Chop celery, carrots, and onions and set them aside.
Add olive oil to a heavy skillet, 3 large chicken breasts, salt, rosemary, thyme, and sage, and cook each side until done, or until internal temperature reaches 165 degrees with a meat thermometer.
Cook one side and cover, flip the chicken and cook the other side until done. *Optionally, you can use 4 cups of precooked chicken.
Next, remove cooked chicken and set aside.
Add chopped celery, carrots, and optional onion and sauté until tender.
Add 2 tablespoons ghee (or oil of choice) 1/4 cup gluten-free all-purpose flour and stir on medium heat until flour is fully incorporated stirring frequently.
Add stock and cook until it begins to thicken.
Add milk of choice and stir until combined.
Cut up or shred cooked chicken and then add it to the pan with celery, onions, carrots, and gravy.
Taste the mixture and add any additional salt if needed.
Optional Add frozen peas
Turn off the heat and add filling to a pie pan with dough.
add the top dough.
Brush with milk, add a few slits to allow venting.
Place pie on a baking sheet to collect any spills and bake for 45 minutes.
Allow to set up and cool for about 15 minutes so the hot filling does not run out.