Step 1In a large pot, peel and halve one of the onions and combine with the beans, celery, carrot, garlic and sage or rosemary. Add water to cover by 2 inches and stir in 2 to 3 tablespoons olive oil. Loosely cover and bring to a boil over medium-high heat. Reduce the heat to a simmer and cook, partially covered, until the beans are very tender, about 1 hour, adding water to pot if needed to keep beans submerged. (If using unsoaked beans, they will absorb more water and cooking can take up to 2 hours.)
Step 2Remove and discard the onion, celery, carrot and sage. Fish out the garlic cloves and place in a small bowl, smashing them with the back of a spoon to form a paste. Stir the garlic paste back into the pot and season the beans with 1 teaspoon salt, or to taste. (The beans can be made a day or 2 in advance and refrigerated.)
Step 3Core and wash the escarole, shaking off any excess water, and roughly chop into large, bite-sized pieces. Finely chop remaining onion. In a large skillet, heat a couple tablespoons of olive oil over medium heat. Add the onion and a little salt to the pan, along with the chile broken in half. Cook, stirring frequently, until onions are softened and pale golden, 7 to 10 minutes. Add the escarole and a little more salt to the pan, stirring occasionally, until the escarole wilts, becomes tender and color darkens, 10 to 15 minutes. Add a little water, as needed, if the mixture begins to stick to the pan.
Step 4Add the cooked escarole to the beans, adding additional water or broth as needed so the mixture has a thick, soup-like consistency. Place the pot over medium heat to warm and marry the flavors, 10 to 15 minutes. Season with 1 teaspoon salt and ¼ teaspoon pepper, or to taste.
Step 5Place a slice of grilled or toasted bread in each soup bowl. Ladle over the soup and top each serving with a drizzle of olio nuovo.