In a large saucepan on low heat, melt butter and add flour. Stir to make a paste or "roux," about 2 minutes. Add celery and onion and cook until they are soft, about 5-7 minutes. Add all other ingredients except green onions. Bring to a boil, and then simmer for 12 minutes. Stir in green onions and more crushed crackers and serve. Very good if made the day before serving and reheated the next day.