1. Preheat the oven to 180°C (350°F).
2. Grease an oval baking dish.
3. Peel the garlic cloves and the onion.
4. Cut the onion and one of the 5 garlic cloves into small pieces.
5. Bake the onion pieces and the pieces of one garlic clove for 5 to 10 minutes. Then let the dish cool down a bit.
6. Wash the vegetables, then slice them into rounds of the same thickness and, if possible, the same diameter.
7. Arrange them in the dish, on top of the roasted garlic and onion, standing upright in successive rows: tomato, zucchini, tomato, eggplant, and so on; intersperse the remaining 5 garlic cloves.
8. Season with salt and pepper, drizzle with olive oil, and sprinkle with Herbes de Provence.
9. Bake for 1 hour and 30 minutes.