Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish.
In the prepared baking dish, combine the rice, chicken broth, olive oil, garlic powder, onion powder, oregano, salt, and pepper. Stir to combine.
Place the chicken breasts or thighs on top of the rice mixture. Season with additional salt, pepper, and oregano.
Cover the dish tightly with foil and bake for 35–40 minutes, or until the chicken reaches an internal temperature of 165°F (75°C), and the rice is fully cooked and tender.
While the chicken bakes, prepare the tzatziki sauce by combining Greek yogurt, grated cucumber, minced garlic, lemon juice, olive oil, dill, salt, and pepper in a bowl. Set aside in the fridge.
Once the chicken and rice are done, remove from the oven and let it rest for 5 minutes.
Top the chicken with a generous amount of tzatziki sauce.
Garnish with cherry tomatoes, feta cheese, olives, and fresh parsley. Serve and enjoy!