Bring a large pot of salted water to a boil. Cook the whole wheat penne according to package directions until al dente. Drain and rinse under cold water to stop the cooking process.

In a medium mixing bowl, whisk together the Greek yogurt, lemon juice, olive oil, dried oregano, garlic powder, salt, and black pepper until smooth.

In a large salad bowl, combine the chilled pasta, cubed grilled chicken, cherry tomatoes, diced cucumber, red onion, and sliced olives.

Pour the Greek yogurt dressing over the pasta mixture. Use a large spatula to fold the ingredients together until every component is evenly coated.

Gently fold in the crumbled feta cheese to maintain its texture.

Refrigerate for at least 30 minutes to allow flavors to meld before serving.