Spray interior of slow cooker with non-stick vegetable spray. In medium skillet over medium heat, crumble and cook sausage until brown. Place in slow cooker.
Add noodles, ricotta, 2 cups mozzarella, pasta sauce and parsley. Stir gently to combine. Cover and cook on low for 4-6 hours.
Five minutes before serving, top with remaining 1 cup mozzarella cheese. Cover to melt cheese.