Put the whole tomatoes in a large roasting tin and drizzle with 2 tablespoons of the oil. Slow-roast in a preheated oven, 150°C (300°F), Gas Mark 2, for 1 hour, or until they look semi-dried.
Meanwhile, cook the pasta in a large saucepan of salted boiling water for about 10–12 minutes, or according to the packet instructions, until al dente.
While the pasta is cooking, heat the remaining oil in a large frying pan. Add the pancetta, garlic, shallots and crushed chillies and cook over a low heat for 10 minutes, or until the shallots are golden and the pancetta nice and crispy.
Toss the roasted tomatoes into the frying pan, reserving a few for garnishing. Drain the pasta, reserving a ladleful of the cooking water. Add the pasta to the sauce and toss over a high heat for a few seconds. Add the reserved cooking water and continue tossing for another 30 seconds. Serve immediately, garnished with the reserved roasted tomatoes and a drizzle of aged balsamic vinegar.