1. Preheat oven to 375 degrees. Bring a medium saucepan of salted water to a boil. Add rice, stir once, and cook until tender, about 25 minutes. Drain.

2. Heat 2 tablespoons oil in a large saute pan over medium-high heat. Add zucchini, garlic, and scallions, and cook, stirring often, for 2 minutes. Reduce heat to medium, and cook, stirring often, until tender, 3 minutes more. Season with salt, and transfer to a bowl.

3. Return pan to medium heat, and add remaining tablespoon oil. Add spinach, and cook for 2 minutes. Add basil, and cook, stirring occasionally, until bright green and wilted, about 2 minutes. Season with salt and pepper. Drain.

4. Whisk ricotta and eggs in a large bowl. Add 1 1/2 cups cooked rice to mixture. Stir in cooked zucchini and spinach-basil mixtures. Add 3/4 teaspoon salt, and season with pepper.

5. Combine Parmesan and remaining cooked rice in a small bowl. Lightly coat a 9-inch round baking dish, 2 inches deep, with oil, and spoon ricotta mixture into dish. Top with Parmesan-rice mixture. Bake until filling is set and top is golden, 35 to 40 minutes. Let stand for 15 minutes before serving.