Chicken and Wild Rice Soup

This is a recipe from Jared's mom, Rosemary. It is one of our favorite soups.
3 cups cooked wild rice
1 large onion, finely diced
2 carrots, finely diced
2 ribs celery, finely diced
1 cup cooked chicken, diced
1/2 cup butter
1 cup flour
8 cups chicken broth
1 cup light cream, or half and half (sometimes I use whole milk if I don't have either of these).
In a 4-5 quart pot, saute the veggies in the butter until they are slightly soft. Add the flour, a little bit at a time, stirring and cooking until all of it is combined. Don't brown it. Slowly add the chicken broth, stirring until the flour-butter-veggie mixture is well blended. Add cooked rice and chicken. Add cream and cook soup until heated, but don't boil. Salt and pepper it to taste.