Heat oil in a large saucepan over medium heat. Add chopped garlic and cavolo nero. Cook until just tender. You may need to add small amount of stock to prevent the leaves from burning and help them maintain their moisture. Remove most of kale mixture leaving some behind to flavor the beans. Add a little more stock and beans then cook until soft and mashable. Toast bread then top with kale first, then beans, a sprinkling of salt, and swirl of olive oil.