- Spray inside of 4-quart slow cooker with cooking spray. Stir together tomato sauce and undrained tomatoes in medium bowl; set aside. Combine ricotta, salt and pepper in small bowl; set aside.
- Spread 3/4 cup tomato mixture over bottom of slow cooker. Layer 3 lasagna noodles over tomato mixture, breaking noodles to fit. Top with 3/4 cup tomato mixture, mushrooms, spinach, ricotta cheese mixture and 1 cup mozzarella cheese. Top with 3/4 cup tomato mixture and 3 remaining lasagna noodles, breaking to fit. Spoon remaining tomato mixture over noodles.
- Cover; cook on LOW 5 to 6 hours or until noodles are tender. Sprinkle with remaining 1 cup mozzarella cheese. Cover; let stand 5 minutes or until cheese melts.
Cooks Tip:Ingredients will fill slow cooker to the top, however, as the lasagna cooks the fresh vegetables shrink down.