Preheat oven to 400° F.
Melt the butter in a large pot on medium-high heat. Add veggies and cook until onions are translucent.
Add chicken, sprinkle with flour and stir to combine, cooking one minute.
Add chicken broth and cook until it thickens.
Season with salt, pepper, thyme, turmeric to your liking, then add sour cream and cook until thick, about 3 minutes.
Remove from heat.
Spoon filling into prepared pie crust until even with the top. Then, roll your second pie crust over the top. Score it with vents (I like to do the flower petal shape, with just 5 slits).
Prepare your egg wash by beating the egg with water, then brush the top of the crust.
Create a tent over the pie on a baking sheet, ensuring the foil does not touch the pie crust. Bake 15 - 20 minutes at 400° F, then remove the tent and continue baking about 40 minutes, until the crust is golden brown.