Preheat oven to 350 degrees. Cook manicotti according to package directions. Drain.
Combine 1/2 cup mozzarella cheese, all the cottage cheese, ricotta cheese, and parmesan cheese. Stir in egg, and parsley. Mix chicken into mixture.
Pour 1/3 cup of sauce into 13x9 baking dish. Open shells and fill with cheese mixture using about 1/4 cup each. Arrange in baking dish. pour remaining sauce over the top. Sprinkle with the remaining mozzarella. Bake uncovered at 350 until bubbly and heated through about 35 minutes. Serves 4