Creamy Chicken and Rice Soup

butter

medium carrots (peeled and diced)

celery stalks (diced)

small onion (finely diced (to hide its existence from picky children))

boneless, skinless chicken breasts (cut into bite-sized pieces)

kosher salt

garlic powder

freshly ground black pepper (to taste)

flour

chicken broth

wild rice or wild/brown rice blend (uncooked)

milk