Preheat your oven to 375°F (190°C).

Lightly grease a 9x13-inch baking dish with cooking spray or a drizzle of olive oil.

Evenly spread the uncooked white rice across the bottom of the prepared baking dish.

Pour the chicken broth carefully over the rice, ensuring it’s fully submerged.

Evenly distribute the cooked chicken atop the rice.

Scatter the diced cucumber, chopped red onion, halved tomatoes, and optional Kalamata olives over the chicken layer.

In a bowl, combine the tzatziki sauce with garlic powder, dried oregano, salt, and pepper. Stir until well mixed and spread evenly over the mixture.

Sprinkle the crumbled feta cheese over the top of the casserole.

Cover tightly with aluminum foil and bake for 45 minutes.

Remove the foil and bake for an additional 10 minutes.

Let cool for a few minutes before garnishing with freshly chopped parsley.