Creating Provençal Eggplant Tomato Gratin is a delightful process. Follow these simple steps to guide you along the way:

1. Preheat the Oven: Preheat your oven to 375°F (190°C).
2. Prepare Eggplant: Sprinkle the eggplant slices with salt and let them sit for about 15 minutes to draw out moisture. Rinse and pat dry.
3. Sauté Onions and Garlic: In a skillet, heat olive oil over medium heat. Add onions and garlic, sautéing until they are soft and fragrant, about 5 minutes.
4. Layer Ingredients: In a baking dish, begin layering the gratin. Start with a layer of eggplant, followed by a layer of tomato slices. Then, add a layer of the sautéed onion and garlic, and sprinkle with basil, oregano, salt, and pepper.
5. Add Cheese: Sprinkle a layer of mozzarella cheese, then repeat the layering process until all ingredients are used, finishing with a generous layer of mozzarella and Parmesan on top.
6. Bake in Oven: Cover the dish with foil and bake for 30 minutes. Remove the foil and bake for an additional 20 minutes, or until the top is golden and bubbling.
7. Let It Rest: Once baked, remove from the oven and let the gratin rest for about 10 minutes before serving. This allows the flavors to meld beautifully.
8. Garnish: Before serving, sprinkle some extra fresh basil on top for an appealing finish.

Following these steps will ensure your Provençal Eggplant Tomato Gratin turns out perfectly, balancing texture and flavor.