1. Place chicken in one layer in large skillet. Sprinkle with 1 teaspoon salt and 1 teaspoon pepper. Add olives and lemon zest, and cover with just enough water to top chicken. Place over medium-high heat, cover and simmer until chicken is cooked through, about 30 minutes.

2. While chicken is cooking, preheat broiler. Brush pita bread slices with 2 tablespoons olive oil and place on large baking sheet. Broil 3 minutes on the highest rack, or until edges are browned. Set aside.

3. In small bowl, combine tomatoes, juice from lemons and remaining salt and pepper. Set aside. In another small bowl, combine yogurt and spinach. Place garlic in small microwave-safe bowl; place in microwave and cook on high heat for 30 seconds. Add garlic to yogurt mixture and stir well to combine. Spread equal amounts of yogurt mixture on each slice of pita bread.

4. When chicken is done, remove from water, shaking off olives or lemon zest. Using two forks, shred chicken to bite-size pieces. Place chicken in large bowl. Add remaining olive oil, rosemary and red pepper flakes. Stir well to combine. Place equal amounts of chicken on each piece of pita bread; top with spoonful of tomatoes.