Combine Ricotta, Mozzarella, grated Parmesan, sugar, egg, nutmeg, parsley, salt and pepper to taste.
Stuff uncooked manicotti generously with the cheese mixture, from both ends.
Arrange manicotti in a single layer in a baking pan.
Bring sauce to a boil and pour over manicotti, covering completely.
Cover baking pan with aluminum foil, crimping the edges to seal tightly.
Bake in a preheated 400 degree Fahrenheit oven for 40 minutes.
Remove foil; sprinkle generously with additional grated cheese.
Bake uncovered for 5 minutes more.
