Cook gnocchi according to package directions. Meanwhile, in a large cast-iron or other heavy skillet, cook chicken and onion in oil over medium heat until chicken is no longer pink; drain if necessary. Stir in the spaghetti sauce, salt and oregano; cook until heated through, 5-10 minutes., Drain gnocchi; gently stir into skillet. If desired, sprinkle with Parmesan cheese.