Trim the spring onions, leaving 5 cm of stem attached, wash and cut into quarters lengthwise. Heat the oil with a few basil leaves in a large pan, add the pancetta cut into small pieces, and sweat for a few minutes before adding the spring onions. Continue to cook over a medium heat for a few minutes. Season with salt and pepper and continue cooking for 8-10 minutes, stirring occasionally. Meanwhile, bring a large pan of salted water to the boil and add the Nonna Rina rigatoni. Cook to al dente then drain, dress with the spring onion sauce and garnish with the remaining basil.