BROWN meat in large skillet; drain. Stir in spaghetti sauce and water. Mix ricotta, 1-1/2 cups mozzarella, 2 Tbsp. Parmesan, egg and parsley.
SPOON 1 cup meat sauce into slow cooker; top with layers of half each of the noodles, broken to fit; and cheese mixture. Cover with 2 cups meat sauce. Top with remaining noodles, broken to fit; cheese mixture and meat sauce. Cover with lid.
COOK on LOW 4 to 6 hours or until liquid is absorbed. Sprinkle with remaining cheeses; let stand, covered, 10 min. or until melted.