Cook your spaghetti in a large pan of salted boiling water according to the packet instructions. Meanwhile, peel and finely chop the garlic. Heat 3 good lugs of extra virgin olive oil in a large frying pan, then toss in the garlic and crumble in the chilli. As the garlic begins to colour, add the prawns and sauté them for a minute. Add the white wine and tomato purée, and simmer for a couple of minutes. Grate the zest of the lemon and roughly chop the rocket. When the pasta is ready, drain it in a colander, reserving a little of the cooking water. Toss the spaghetti with the sauce, squeeze in the lemon juice, add half the chopped rocket, adding a little of the reserved cooking water if you want to loosen the sauce a bit, and correct the seasoning with sea salt and black pepper. Divide between 4 plates and sprinkle with the grated lemon zest and the rest of the rocket leaves.