In a very large bowl combine chicken, cucumber, celery, olives, walnuts, artichokes, and green onions. Set aside.
In a blender container or food processor bowl combine lemon (including peel), olive oil, vinegar, sugar, salt, and pepper; cover and blend until nearly smooth. Pour dressing mixture over chicken mixture; toss to combine. Cover and chill up to 2 hours.
Serve salad on spinach leaves and sprinkle with parsley, if desired. Makes 6 servings.