1. Cook manicotti shells according to package directions, omitting salt; drain and set aside.
2. Combine next 8 ingredients; cover and cook sauce over low heat for 1 hour.
3. Preheat oven to 350 degrees. Cook spinach according to package directions, omitting salt. Drain; place on paper towels and squeeze until barely moist.
4. Combine spinach, cottage cheese, Parmesan cheese, and nutmeg. Stuff manicotti shells with spinach mixture and arrange in a 13- by 9- by 2-inch baking dish coated with nonstick cooking spray.
5. Pour tomato sauce over manicotti. Bake for 45 minutes. Garnish with parsley.