Heat the olive oil in a large saucepan over a low heat, add the garlic, rosemary and chilli and cook, stirring, until the garlic begins to colour. Add the tomato purée and chickpeas and cook, stirring, for 2–3 minutes, then add the stock. Bring to the boil, then reduce the heat and simmer gently for 15 minutes.
Transfer half the mixture to a food processor and process until smooth, then return to the pan. Bring to the boil and season with salt if necessary. Add the pasta and cook, stirring frequently, until al dente. Add some boiling water if the soup looks too dry, but the final dish should be thicker than the average soup, yet moister than a classic bowl of pasta.
Leave the soup to stand for 2–3 minutes before serving with a scattering of grated Parmesan and a drizzle of extra virgin olive oil.