Preheat oven to 375°F heat 3 tablespoons oil in a large skillet over medium heat. Add leek and garlic, season wiht salt and pepper, and cook until soft, about 4 minutes. Spread in an 9-inch gratin (round) baking dish.
Arrange vegetables on leeks in slightly overlapping circles, alternating zuccini, squash tomatoes, and egg plant.
Top with wine, 1 tablespoons oil, oregano, salt and pepper. Bake 30 minutes. Drizzle with remaining oil. Bake until vegetables are tender, 30 minutes more. Serve with Parmesan.