Preparation - Wash the asparagus; remove any woody areas from the lower ends of the spears; cut into 1" pieces. In a stockpot or large saucepan, simmer the asparagus, celery, chopped onions and 1/2 cup of the chicken broth for about ten minutes or until the asparagus is tender. Remove from heat, cool, then puree the asparagus mixture in a blender or food processor or strain it in a food mill until smooth; set aside. Melt the butter in the bottom of the stockpot or saucepan. Add the remaining chicken broth. Whisk in the flour and salt, while bringing to a low boil over medium heat. Reduce heat and simmer for about 10 minutes. Stir in the asparagus puree, milk, and cream; cook on low heat until well blended and heated through.