Cook and drain broccoli as directed on package, using minimum cook time. In large bowl, mix chicken, 2 cups of the cheese blend, the pepper, both soups, sour cream, mushrooms and broccoli.
Spray 5-quart slow cooker with cooking spray. Spread one-fourth of the chicken mixture in slow cooker. Layer with 3 of the uncooked noodles (breaking noodles as needed to fit), one-fourth of the chicken mixture and 1/2 cup of the cheese blend. Repeat layers twice. Sprinkle with Parmesan cheese.
Cover; cook on Low heat setting 3 hours 30 minutes or until bubbly and noodles are tender. Let stand 10 minutes before serving. Sprinkle with additional freshly ground pepper, if desired.