Luby's Broccoli and Cheese Soup

A friend of mine gave me this recipe, and next time I make it I'm going to have to cut it in half. I've made it once, and half of it is still in my freezer. It was very good though....

8 cups chicken broth
1 can condensed cream of celery soup (I used 98% ff)
3/4 cup chopped onion
3/4 cup chopped celery
2 cups milk (again I used ff)
1/4 cup cornstarch
1/4 cup water
3 cups cooked broccoli florets
3 cups (1 lb) velvetta 2%

in large pot combine, broth, soup, onion, celery. Bring to a boil, reduce heat and simmer for 20 minutes. Add milk and bring to a boil.

in a small bowl mix cornstarch and water until cornstarch is completely dissolved. Gradually whisk cornstarch mixture into boiling soup. Reduce heat and simmer for 5 minutes. Add Broccoli and cheese, stirring until cheese is melted.