Creamy Chicken Soup

This is basically the recipe in the family cookbook (I've tweaked it a bit through the years).
Lots of people ask for the recipe, so I'm adding it on here for easy sharing.

In a soup pot saute:
3 Tbs butter
1 onion
1-2 celery stalks

Thicken a little by adding:
1-2 Tbs flour, let bubble for about 1 minute.

Whisk in:
2 Cans chicken broth or bone broth

Add and simmer until tender (about 20 minutes):
2-3 medium red potatoes, chopped
4-5 carrots, chopped

Add:
3/4 cup frozen peas
1 tsp season salt
1/2 tsp thyme
1/2 tsp rosemary (fresh or dried)
salt and pepper to taste
powdered garlic to taste
cooked chicken (about 2-3 breasts)

Simmer 10 more minutes, then add:
1 cup of whole milk.
Add more or less milk to your liking.