Drain chickpeas (discard liquid) and place in a large saucepan, add stock and bring to the boil, then cook over low heat until tender (1-1½ hours). Remove half the chickpeas and process to a coarse texture in a food processor, then return to soup.
Heat olive oil in a frying pan over medium heat, add pancetta, onion, garlic and rosemary and cook until tender (10-15 minutes). Add to soup with chicory, season to taste and stir occasionally until tender (30 minutes). Serve hot drizzled with extra-virgin olive oil.