Heat oil in large frying pan over medium high heat. Cook potatoes, stirring frequently until tender-crisp. Stir in chicken, and cook until no longer pink. Reduce heat to medium. Stir in condensed soup, milk and onion powder. Arrange vegetables on top, and sprinkle with parsley, marjoram and basil. Cover, and simmer over low heat until chicken is cooked through, and vegetables are tender, about 5 minutes. Remove from heat, and stir in Parmesan.