Soak all the beans overnight in a large bowl with enough water to cover. (Or, quick-soak the beans: Place them in a heatproof bowl and cover with boiling water by 3 inches. Let stand for 1 hour.) Rinse the beans and transfer them to a pot. Add fresh water to cover the beans by 3 to 4 inches. Add the halved onion, smashed garlic, bay leaves, and rosemary and bring to a boil. Salt the water, reduce the heat to a low boil, and cook until tender, 35 to 45 minutes.
Discard the rosemary and bay leaves. Measure out and set aside half the beans. With an immersion blender, puree the remaining beans and cooking liquid in the pot (or transfer the beans to a blender and puree in batches).
Meanwhile, in a large soup pot, heat the oil (4 turns of the pan) over medium to medium-high heat. Add the fennel, leek, carrots, celery, sliced onion, chopped garlic, thyme, salt, and pepper. Cover and cook, stirring occasionally, until the vegetables have softened, about 10 minutes.
Add the stock, cabbage, kale, passata, reserved beans, bean puree, Parm rind, and some nutmeg. Adjust the seasonings. Bring to a bubble, then reduce to a simmer.
Preheat the oven to 350°F. Spread the bread on a baking sheet and toast until deep golden. Add the bread to the soup.
Serve in warmed shallow bowls topped with sliced onion, a generous drizzle of EVOO, and grated Parm.
TIP: Instead of store-bought passata or tomato puree, you could make this with 2 pounds of tomatoes, peeled and diced.
VARIATION: TUSCAN RIBOLLITA
This vegetable and stale bread soup is a Tuscan staple. Ribollita is said to be “done” when a soup spoon can stand straight up in the soup—which can happen because the bread swells in the rich broth, making
the soup (already thick with stewed vegetables) support the spoon. My favorite ribollita, other than the soup I prepare with the bounty of our garden, is the ribollita at Taverna del Grappolo Blu, a small restaurant in Montalcino, Italy.
When you prepare ribollita, you must serve it according to tradition. The soup is always garnished with shaved or thinly sliced onion and dressed with a drizzle of good-quality EVOO. The next day, this soup can be so thick that you can fry patties of it like mounds of hash browns. John likes his topped with basted or over-easy eggs.