1. Preheat the Oven: Start by heating your oven to 200°C (400°F). Grease a baking dish with a bit of olive oil.
2. Layer the Vegetables: Arrange the sliced zucchinis, eggplant, and peppers in the prepared baking dish. Drizzle with olive oil to lightly coat the vegetables.
3. Prepare the Breadcrumb Mixture: In a small bowl, combine the breadcrumbs, grated Parmesan, salt, basil, thyme, and minced garlic.
4. Sprinkle and Bake: Evenly distribute the breadcrumb mixture over the arranged vegetables in the baking dish. Place in the oven and bake for 45 minutes, or until the vegetables are tender.
5. Add Tomatoes and Mozzarella: After the initial baking, take the dish out of the oven. Arrange sliced tomatoes and mozzarella cheese over the baked vegetables. Sprinkle with a little more salt.
6. Final Bake: Increase the oven temperature to 205°C (400°F). Return the dish to the oven and bake for an additional 20 minutes, or until the mozzarella is melted and bubbly. In the last few minutes, you can sprinkle additional Parmesan on top for a golden finish.
7. Serve: Allow the gratin to cool slightly before serving. This dish is perfect on its own or as a side to a larger meal.

Conclusion:

This Vegetable Gratin showcases the beauty of garden vegetables under a melty cheese topping, making it an irresistible addition to any table. With its layers of flavor, this dish not only satisfies the taste buds but also provides a comforting, nourishing meal. Enjoy the process of creating this delightful gratin and the pleasure of sharing it with family and friends.