In a 5-qt. slow cooker, combine first 7 ingredients. Cook, covered, on low until chicken is tender, 6-8 hours., Stir in Alfredo sauce and tortellini. Cook, covered, until tortellini is tender, 15-20 minutes. If desired, top with Parmesan cheese and basil., Freeze option: Freeze cooled, cooked mixture in freezer containers. To use, partially thaw in refrigerator overnight. Microwave, covered, on high, in a microwave-safe dish until heated through, stirring gently; add water if necessary.