In a small bowl, mix the first 6 ingredients; stir in 1/2 cup mozzarella and 1/2 cup Parmesan cheese.
In another bowl, mix marinara sauce and water; spread 3/4 cup sauce onto bottom of a 13x9-in. baking dish coated with cooking spray. Fill uncooked manicotti shells with ricotta mixture; arrange over sauce. Top with remaining sauce.
Bake, covered, until pasta is tender, 50 minutes.
Sprinkle with remaining 1/2 cup mozzarella and 1/2 cup Parmesan cheese. Bake, uncovered, until cheese is melted, 10-15 minutes longer. If desired, top with additional parsley and serve.