Step 1

Sort and wash the beans; place in a large Dutch oven. Cover with water to 2 inches above the beans; cover and let stand 8 hours. Drain the beans. Place the beans in a 5- to 6-quart slow cooker. Add the stock, tomato, salt, pepper, garlic, and rosemary sprigs. Cover and cook on LOW until the beans are tender, about 7 hours.

Step 2

Lightly mash the bean mixture with a potato masher, breaking up the tomato and garlic. Add the sausage to the slow cooker; cover and cook on LOW until thoroughly heated, about 20 minutes. Add the spinach and parsley, stirring just until the spinach begins to wilt. Discard the rosemary sprigs. Ladle the stew into bowls; drizzle evenly with the oil before serving.