1. Drain spinach well, pressing between paper towels. Stir together spinach, chicken, next 5 ingredients, and 3 cups Italian cheese blend in a large bowl.
2. Spoon one-fourth of chicken mixture into a lightly greased 6-qt. slow cooker. Arrange 3 noodles over chicken mixture, breaking to fit. Repeat layers twice. Top with remaining chicken mixture and 1 cup cheese. Cover and cook on LOW 3 1/2 hours or until noodles are done, mixture is bubbly, and edges are golden brown. Uncover and cook on LOW 30 minutes. Sprinkle with basil. Let stand 10 minutes before serving.
* Reduced-fat Alfredo sauce may be substituted.
** Reduced-fat cream of mushroom soup may be substituted.