Follow these simple steps to create your Dump-and-Bake Chicken Tzatziki Casserole:

1. Preheat the Oven: Preheat your oven to 375°F (190°C).
2. Prepare the Baking Dish: Lightly grease a 9×13-inch baking dish with cooking spray or olive oil.
3. Layer the Chicken: Place the chicken breasts in a single layer in the baking dish. Season with salt and pepper.
4. Add Tzatziki Sauce: Spread the tzatziki sauce evenly over the chicken, ensuring each piece is well coated.
5. Add Vegetables: Scatter the cherry tomatoes, cucumber, and red onion over the chicken and tzatziki sauce.
6. Add Rice: Evenly distribute the cooked rice around the chicken and vegetables.
7. Top with Feta: Sprinkle the crumbled feta cheese on top of the entire dish.
8. Drizzle Olive Oil: Drizzle the olive oil over the top for added flavor and moisture.
9. Cover with Foil: Cover the baking dish with aluminum foil to keep the chicken moist while baking.
10. Bake: Place the dish in the preheated oven and bake for 25 minutes.
11. Uncover: After 25 minutes, remove the foil and bake for an additional 15-20 minutes, or until the chicken is cooked through (internal temperature should reach 165°F/75°C) and the top is slightly golden.
12. Rest and Garnish: Once baked, remove from the oven and let it rest for 5 minutes. Garnish with fresh dill or parsley before serving.

These simple steps will guide you in preparing this delightful casserole effortlessly.