Sauté the onion till golden in oil, lard or butter, then add in stock. Whisk in flour. If you brined your chicken you won’t need much salt as your stock will have some, but I like to sprinkle in a bit as I go along with black pepper and thyme.
Then add your carrots. I like them crunchy so I add after I make the roux of stock, onion and flour.
At the end throw in chicken and peas let the whole mess thicken, then pour into shell, put top crust on, cover edges with pie shield or tin foil. Bake 425 till golden, about an hour.