In a large skillet, cook chicken and onions until chicken is no longer pink. Add tomato sauce, basil, and pizza seasoning. Mix well and set aside.
In a bowl, combine 1 cup mozzarella cheese, cottage cheese, and parmesan cheese. (Refrigerate remaining mozzarella cheese until lasagna cooks).
Spread 1/4 chicken mixture into 6-quart slow cooker; top with 5 noodles, broken into pieces to fit. Spread with half the cheese mixture and 1/4 of the chicken mixture. Top with 5 noodles remaining cheese mixture and 1/4 chicken mixture.
Top with remaining 5 noodles and remaining chicken mixture. Cover and cook on LOW heat for 5 hours, or until noodles are done. Sprinkle top of lasagna with remaining mozzarella cheese. Cover and let stand for 10 minutes before serving.