Consider serving this with a grilled leg of lamb and braised greens. Or turn this side dish into a main dish by adding a big salad and some good bread and butter. The recipe can easily be doubled.

Steps

1. Preheat oven to 350 degrees.
2. In a saucepan, sauté the onion in 1 Tbsp. of the olive oil over moderate heat until golden. Mince the garlic and add half of it to the onions, reserving the rest. Cook and stir for one minute, then add the sage and tomato paste. Mix the tomato paste into the onion mixture and sauté for two more minutes, scraping up any brown bits that accumulate on the bottom of the pan.
3. Add the beans and ½ to ¾ cup of their reserved cooking liquid. (If using canned beans, substitute water for the cooking liquid.) The mixture should be somewhat soupy. Season with salt and pepper. Partly cover the pot and let the beans simmer for 10 minutes.
4. Meanwhile, peel the parsnip and carrot and cut each into ½-inch pieces. Steam the parsnip until tender, about 5 minutes, then steam the carrot until soft, about 4 minutes. Add the vegetables to the bean mixture and simmer 2 minutes longer. Add more bean broth or water if necessary.
5. Mix the breadcrumbs with the remaining garlic and the parsley, and season with salt and pepper.
6. Lightly oil an 8-by-10-inch baking dish or gratin dish. Turn out the bean and vegetable mixture into the pan. Sprinkle the seasoned breadcrumbs over the beans and vegetables and drizzle with the remaining olive oil.
7. Bake for 25 to 30 minutes, or until the gratin begins to bubble. Serve warm.