This vegetable gratin is an excellent accompaniment for grilled lamb chops or roast leg of lamb, or broiled or roasted chicken. It also makes a very nice lunch accompanied with some good bread and a small salad. Don’t overload it with cheese—it should be light in texture. And don’t worry about leftovers; the gratin is delicious reheated.
Preheat the oven to 450°F. Brush 2 large baking sheets with olive oil. Cut the eggplant and zucchini lengthwise into ¼-inch-thick slices. Put them on the baking sheets and brush with about 3tablespoons oil. Lightly sprinkle with salt and pepper. Bake until almost cooked through but not browned, 10 to 15 minutes. Let stand until cool enough to handle.
Preheat the oven to 350°F. To assemble the gratin, spread the tomato sauce over the bottom of a 9-inch square baking dish. Arrange half the eggplant slices on the sauce, then make a layer of half the zucchini slices, placing them at right angles to the eggplant slices. Layer half the tomatoes over the zucchini. Lightly season with salt and pepper and sprinkle with half the basil. Top with half the cheese. Repeat the layers with the remaining ingredients. Bake until the cheese melts but doesn’t brown, about 15 minutes. Let cool 5 minutes and cut into 3-inch squares. Serve with meat, chicken, or fish, or simply by itself.