Melt half of the butter in a pan and, when it is sizzling, add the tomatoes. Season with salt and a dash of pepper and then cook over medium heat for about 10 minutes, until it is thick.

Cook the pasta in a large pan of boiling salted water, following the packet instructions. Meanwhile, heat a large non-stick frying pan over high heat. Add the oil and the rest of the butter and, when it is sizzling, add the prawns and garlic.

Over the highest heat possible, cook the prawns until they are quite bright and the undersides are golden and crusty in places. Turn them with tongs and, when they are cooked, scatter them with salt and cook for few seconds.
Drain the pasta, keeping a cupful of the cooking water. Add the tomato sauce to the prawns, along with the cream and parsley. Heat until just bubbling.

Add the pasta and toss well. If it seems like you need it, add a little of the cooking water to help the sauce coat the pasta. Serve immediately with a grinding of pepper.