Preheat oven to 450. Slice tomatoes. Drain in strainer or sieve and discard tomato liquid or save for another use
Heat 2 T. butter and the oil in large skillet over medium heat. When foam subsides, add onion. Sauté until soft, about 8 minutes.
Trim and rinse zucchini. Cut into thin slices. There should be about 3 cups. Heat remaining 2 T. butter in another large skillet. Sauté zucchini 4 to 7 minutes and drain well on paper towels. Add garlic to sautéed onion and sauté 2 minutes. Stir in tomatoes, basil, nutmeg, salt and pepper to taste.
. Cook over medium high heat, stirring occasionally until moisture evaporates, about 8 minutes. Beat eggs lightly in large bowl with wire whisk. Whisk in ricotta, cream and Parmesan. Arrange half the zucchini slices in layer on bottom of 9" pie plate. Top with tomato mixture, spreading evenly. Arrange remaining zucchini slices over tomato layer; pour ricotta mixture over all. Bake 10 minutes at 400. Reduce heat to 375. Continue baking until top is brown and slightly puffed, about 25 minutes more. Cut into wedges to serve. Serves 6