Creating Easy One-Pan Baked Tilapia and Vegetable Casserole is straightforward. Follow these steps for a delicious meal:

1. Preheat the Oven: Preheat your oven to 400°F (200°C).
2. Prepare the Baking Dish: Lightly grease a large baking dish or sheet pan with olive oil.
3. Arrange Vegetables: Place the broccoli, cherry tomatoes, bell peppers, and onion in the baking dish. Spread them out evenly.
4. Season the Vegetables: Drizzle with olive oil and sprinkle with salt, pepper, garlic, paprika, oregano, and thyme. Toss to coat the vegetables well.
5. Add Tilapia: Place the tilapia fillets on top of the seasoned vegetables.
6. Season the Fish: Squeeze the juice of half a lemon over the tilapia and season with additional salt and pepper if desired. Lay lemon slices on top of the fish.
7. Bake: Place the baking dish in the preheated oven and bake for 25-30 minutes, or until the tilapia flakes easily with a fork and the vegetables are tender.
8. Garnish: Once cooked, remove from the oven and garnish with fresh parsley if using.
9. Serve: Serve warm, directly from the baking dish, alongside your favorite grain or bread.

These steps will guide you in creating this incredible casserole effortlessly.