Italian sausage can be substituted with ground chicken, turkey or beef sausage. If using beef sausage or ground beef, replace the chicken bouillon and chicken broth with beef bouillon and beef broth, same quantities apply. Please note that the soup will thicken even more when cold, when reheating you may need to add a bit of milk, add ¼ cup at a time. Preferably heat it on the stove top if you will be adding more milk. You can add more red pepper flakes, if you would like the soup on the spicy side.