Wisconsin Cheese Soup

½ c finely chopped onion
4 t butter
4 t flour
1 ½ t cornstarch
4 c chicken stock
4 c milk
1 c cooked carrots
1 c cooked celery
1/8 t paprika
1/2 pound shredded cheddar cheese
1/2 pound velveeta cheese


Saute onions, carrots and celery in butter until tender. Add flour and cornstarch blending well. Add chicken stock and milk gradually, stirring constantly. When boiling add paprika and cheeses. Cook over low heat until cheese is melted. Add extra rue and salt if necessary.