Chicken Pot Pie Soup

chicken, cooked and diced

unsalted butter

yellow onion, diced

celery stalks, diced

fresh broccoli florets, chopped

all purpose flour

chicken broth

heavy cream

milk (I used skim)

crushed red pepper flakes

kosher salt

ground black pepper

cheddar cheese, shredded

package pie crust (I used Pillsbury), thawed