Cook mostaccioli according to package directions. Meanwhile, in a large saucepan, cook the turkey and onion over medium heat until the meat is no longer pink;drain if necessary.
Stir in the tomatoes, tomato paste, water, oregano, salt and pepper. Bring to a boil. Reduce heat; cover and simmer for 15 minutes.
In a small bowl, combine cottage cheese and marjoram; set aside.
Spread 1/2 cup meat sauce into an 9"x9" baking dish coated with cooking spray. Layer with half of the mostaccioli, meat sauce and mozzarella cheese. Top with cottage cheese mixture. Layer with remaining mostaccioli, meat sauce and mozzarella cheese. Sprinkle with Parmesan cheese.
Bake, uncovered, at 350 for 30-40 minutes or until bublby and heated through.