Cream of Broccoli Soup

Ingredients 4 cups chicken broth 1 (10 3/4ounce) can  cream of celery soup 1 (16 ounce) package frozen chopped broccoli 1/2 cup butter or margarine 1 medium onion, chopped 1/4 cup flour 2 cups milk 1/2 tsp. salt 1/2 tsp. pepper 1/2 cup shredded cheddar cheese Bring broth and soup to a boil in a large saucepan over medium-high heat.  Add broccoli, return to boil and reduce heat.  Cover and simmer for 5 minutes. Heat butter in a skillet and add onion.  Saute until tender.  Add flour and cook for 1 minute.  Add milk to skillet.  Cook, stirring continually, until thickened, about 5 mintues.  Add salt and pepper. Add milk mixture to broccoli mixture.  Simmer over low heat for about 10 minutes, stirring frequently.   Ladle soup into serving bowls and top with cheddar cheese.