Cook the pasta in a large pan of boiling salted water, according to packet instructions. Meanwhile, peel and finely slice the garlic, deseed and finely slice the chilli, then put both into a large frying pan on a medium heat with a lug of oil. Fry until lightly golden, then stir in the prawns, peas and tomato purée, add a few swigs of boiling cooking water from the pasta pan, and simmer slowly on a low heat until the pasta is ready. Once cooked, drain the pasta, reserving a cupful of cooking water. Season the sauce to perfection, then toss with the pasta. Finely grate over the Parmesan and mix together, loosening with a little cooking water, if needed. Divide between your bowls and serve right away.