In small bowl, mix all dipping sauce ingredients; set aside. In large bowl, mix feta cheese, mozzarella cheese, cucumber, tomato, olives, salt and pepper.
Heat 12-inch nonstick skillet over medium heat until hot. Sprinkle 1/2 cup cheese mixture onto half of each tortilla. Fold untopped half of each tortilla over cheese mixture; gently press down with pancake turner.
Cook quesadillas, 3 at a time, in hot skillet about 2 minutes on each side, gently pressing down with pancake turner, until tortillas are lightly browned and crisp and cheese is melted. Remove from skillet; place on cutting board. Cut each quesadilla in half. Serve warm with dipping sauce.