
This gratin can be eaten as a side dish or as main course. Leftovers of the gratin make a perfect lunch the next day.
Preheat the oven to 180 degrees. Grease baking dish with olive oil.
Heat a little olive oil in a large frying pan. Add onions, garlic and a pinch of salt. Cook, stirring occasionally, for 5 minutes, until completely softened. Stir in the basil and thyme. Spread on the bottom of the prepared baking dish.
Toss the sliced vegetables with the remaining olive oil and salt, and pepper.
Cover the dish with aluminum foil and bake until the vegetables are softened, about 30 to 35 minutes.
Uncover and sprinkle with the Parmesan. Continue baking until cheese begins to melt, about 20 minutes.