Step 1: Preheat your oven to 375°F (190°C). Lightly grease an 8×8 inch (20×20 cm) baking dish or similar-sized casserole dish.
Step 2: Heat the olive oil in a large skillet over medium heat. Add the chopped onion and sauté for 3-5 minutes until softened. Add the minced garlic and cook for another minute until fragrant.
Step 3: Stir in the chopped zucchini to the skillet. Cook for 5-7 minutes, stirring occasionally, until the zucchini is slightly tender but still holds its shape. Remove from heat.
Step 4: In a large mixing bowl, combine the cooked zucchini mixture, cooked rice, vegetable broth, dried Italian seasoning, and half of the shredded mozzarella cheese. Mix thoroughly until all ingredients are well combined.
Step 5: Transfer the rice and zucchini mixture into the prepared baking dish. Spread it evenly, then sprinkle the remaining shredded mozzarella cheese over the top.
Step 6: Bake for 20-25 minutes, or until the casserole is hot and bubbly, and the cheese on top is melted and lightly golden. Let it rest for a few minutes before serving.
Notes
Leftover casserole keeps beautifully! Store any extra portions in an airtight container in the refrigerator for up to 3-4 days.
To enjoy leftovers, reheat individual portions in the microwave until warm, or for a crispier top, warm the whole dish in an oven preheated to 350°F (175°C) for about 15-20 minutes.
This casserole is wonderful on its own as a light meal, or serve it as a hearty side dish alongside grilled chicken or fish, perhaps with a fresh garden salad for a complete dinner.
For the best texture and to prevent a watery casserole, be careful not to overcook the zucchini in Step 3; it should still have a slight bite and hold its shape as it will finish cooking in the oven.