Start by preheating your oven to 375°F (190°C). A properly heated oven ensures even cooking for both the chicken and rice.
In a large bowl, combine olive oil, minced garlic, lemon juice, oregano, thyme, salt, and pepper, whisking until well blended. Add the chicken thighs or breasts, ensuring each piece is thoroughly coated in the marinade. Let the chicken marinate for at least 20 minutes, or up to 2 hours for a deeper flavor.
Place the frozen vegetable mixture in the baking dish. After place the rice on the top of vegetables.
Remove the marinated chicken from the bowl and place it on top of the rice mixture in the baking dish. Pour any leftover marinade over the chicken and rice for extra flavor. Add the chicken broth or water and season with salt and pepper.
Cover the baking dish with aluminum foil and place it in the preheated oven. Bake for 35-40minutes, until the rice is tender and the chicken reaches an internal temperature of 165°F (75°C). If the rice appears dry while cooking, add a bit more broth or water as needed.
For an extra crispy finish, remove the foil during the last 5 minutes of cooking and switch the oven to the broil setting. Broil until the chicken skin (or to player) turns golden brown and slightly crispy.
When fully cooked, take the dish out of the oven and let it rest for 5 minutes before serving.