In a large cast-iron or other heavy skillet, cook beef, onion and garlic until meat is no longer pink; drain. Add the tomatoes, water, tomato paste, parsley, oregano and salt. Stir in pasta; bring to a boil. Reduce heat; cover and simmer until pasta is tender, 20-25 minutes, stirring once.
Combine cheeses; drop by rounded tablespoonfuls onto pasta mixture. Cover and cook for 5 minutes. If desired, sprinkle with additional dried oregano.