In a small bowl, mash half of the beans with a masher or the back of a spoon; set aside. Heat the oil in a large soup pot over medium-high heat. Add the onion, carrot, celery, zucchini, garlic, thyme, sage, salt and pepper, and cook, stirring occasionally, until the vegetables are tender, about 5 minutes. Add the broth and tomatoes and bring to a boil. Add the mashed and whole beans and the spinach leaves; cook until the spinach is wilted, about 3 minutes more. Serve topped with the Parmesan, if desired. Per serving: 143 calories, 20g carbohydrates, 8g protein, 4g fat (0.5g saturated), 5g fiber, 0mg cholesterol, 323mg sodium