In a large skillet over medium heat brown the ground beef, Italian sausage and onion. Add salt, pepper, Italian seasoning, parsley, garlic powder, Worcestershire sauce, tomato paste, tomato sauce, sugar, and water. Stir and simmer 15-20 minutes. (You could make the sauce in advance!)
Spread a fourth of the meat sauce into the bottom of your slow cooker. Arrange a third of the noodles over the sauce (break the noodles to fit, if necessary). Combine the mozzarella, cottage cheese and parmesan cheese; spoon a third of the mixture over noodles. Repeat layers twice. Top with remaining meat sauce and sprinkle with extra mozzarella cheese, if desired.
Cover and cook on low for about 4-5 hours or until noodles are tender.