n a large bowl, mix ricotta, spinach, 1 cup mozzarella cheese, 1/4 cup Parmesan cheese, egg, parsley and seasonings. In a large bowl, mix spaghetti sauce and water; spread 1 cup into a greased 13x9-in. baking dish.
Fill uncooked manicotti shells with ricotta mixture; arrange over sauce. Pour remaining spaghetti sauce mixture over top. Sprinkle with remaining mozzarella cheese and Parmesan cheese. Refrigerate, covered, overnight.
Remove from refrigerator 30 minutes before baking. Preheat oven to 350°. Bake, uncovered, 40-50 minutes or until manicotti is tender.
Freeze option: Cover and freeze unbaked casserole. To use, partially thaw in refrigerator overnight. Remove from refrigerator 30 minutes before baking. Preheat oven to 350°. Bake casserole as directed, increasing time as necessary to heat through and for a thermometer inserted in center to read 165°.