Preheat oven to 350. Prepare a 10 "x 1 1/2" pie plate with cooking spray; set aside. In a skillet, cook chicken and onions until chicken is no longer pink. Stir in tomatoes, tomato sauce, Italian seasoning, and salt. Heat to boiling; reduce heat. Cover and simmer ten minutes, stirring occasionally. Meanwhile, combine fettuccine and mozzarella cheese in a small bowl. Spread mixture into prepared plate; press evenly on bottom and up sides. Meanwhile, combine cottage cheese and egg in a small bowl; spread mixture over fettucine in pan. Sprinkle top evenly with chicken mixture and parmesan cheese. Bake, uncovered for 30 minutes, or until hot in center. Let stand 10 minutes before cutting.