Preheat your oven to 375°F (190°C). In a 9x13 inch baking dish, spread the rinsed rice evenly across the bottom.
Pour the chicken broth over the rice, ensuring it is evenly covered.
Season the chicken breasts with garlic powder, onion powder, oregano, salt, and black pepper. Place the seasoned chicken on top of the rice.
Scatter the halved cherry tomatoes around the chicken in the baking dish.
Cover the dish tightly with aluminum foil and bake for 30 minutes.
While the chicken and rice are baking, prepare the tzatziki sauce by combining the Greek yogurt, lemon juice, diced cucumber, dill, and olive oil in a bowl. Mix well and refrigerate until ready to serve.
After 30 minutes, remove the foil and bake for an additional 10-15 minutes, or until the chicken is cooked through (internal temperature should reach 165°F) and the rice is tender.
Let the dish rest for 5 minutes before serving. Serve the chicken and rice topped with a generous dollop of tzatziki sauce.