Meanwhile, in another pot, heat 2 tablespoons of the oil. Add the pancetta and cook over moderate heat until crisp, 4 minutes. Add the shallots, celery, onion, carrot and fennel, and cook until softened. Add the garlic, crushed pepper and bay leaves and cook, stirring, until fragrant. Add the tomato paste and cook, stirring, for 2 minutes. Stir in the tomatoes and broth; bring to a boil. Simmer over low heat for 1 hour. Add the beans and enough cooking liquid to thin out the soup. Discard the bay leaves; season with salt and pepper.