Preheat oven to 375. Prepare a 11"x7" casserole dish with cooking spray; set aside. In a large skillet cook chicken and onions until chicken is no longer pink. Add tomato sauce, pizza seasoning, and salt. Cook until bubbly. Spread into prepared dish. In a small bowl combine, mozzarella cheese and sour cream. Spoon over chicken mixture. Unroll crescent roll dough over chicken mixture in dish. In a small bowl, combine parmesan cheese, and egg whites. Spread evenly over dough in dish. Bake for 20 minutes, or until golden brown.