Baked Eggplant, Zucchini and Parmigiano Tortino

Preheat oven to 350 degrees. Oil a 9 inch (2 quart) round or square flame-proof baking dish. In a large, heavy skillet cook onion in 2 tablespoons of the oil, over moderate low heat, stirring occasionally, until golden brown, about 15 minutes. Transfer to a small bowl. In the skillet, heat 4 tablespoons of oil over moderate heat until hot but not smoking and cook eggplant, stirring, for 3 minutes. Add zucchini and yellow squash and cook, stirring, until tender, about 5 minutes. Stir in onion, 1/2 teaspoon salt and 1/8 teaspoon pepper. In a large bowl, beat eggs and stir in remaining salt and pepper, 1 tablespoon oil, vinegar, cream and 2/3 of a cup of cheese. Stir in vegetables. Pour vegetable mixture into prepared baking dish, spreading evenly, and bake, covered with foil, in the middle of the oven for 35 minutes. Tortino may be prepared up to this point 3 days ahead and chilled, covered. Sprinkle Tortino with the remaining cheese and bake, uncovered until the eggs are set, about 15 minutes more. Transfer Tortino to a rack. Preheat broiler. Broil Tortino about 6 inches from the heat until the cheese is golden, about 3 minutes. Let Tortino stand for 5 minutes. Cut into serving pieces. Serves 6.