Preheat oven to 350 degrees F. In a large bowl, combine chicken, zucchini, soup, onion, broth, 1 teaspoon of the Greek seasoning, and the garlic. Transfer mixture to an ungreased 3-quart rectangular baking dish.
Coat pita wedges with cooking spray; sprinkle with the remaining 1/2 teaspoon Greek seasoning. Sprinkle pita wedges, tomatoes, cheese, and olives on top of chicken mixture. Bake, uncovered, about 20 minutes or until heated through. Makes 4 servings.