Tuscan White Bean, Sausage, and Kale Soup

Drain beans; place in a large saucepan with broth and bring to a full boil. Add kale; stir until wilted. Stir in onions, carrots, tomatoes with their juice, 1 tablespoon of the sage, garlic and bay leaf. Carefully pour hot mixture into a 6-quart to 7-quart slow-cooker. Cover; cook on low-heat setting 9 to 11 hours, until beans are tender. Discard bay leaf; stir in vinegar, salt, and pepper. Turn slow-cooker to warm setting. Cut sausages into bite-size pieces; cook in a large nonstick skillet in 1 tablespoon of extra-virgin olive oil, until golden and cooked through. Stir into soup with remaining 1 tablespoon chopped sage. Ladle into bowls; drizzle each serving with extra-virgin olive oil and sprinkle with cheese, if desired.