1.Preheat oven to 220°C (200°C fan-forced).
2.Make small incisions all over lamb and insert a sliver of garlic into each. Season Lamb all over with salt and pepper and dried oregano.
3.Pour oil into a roasting tray and add meat. Add tomatoes and roast 20 minutes. Turn meat, spoon tomatoes over, then cook a further 25 minutes.
4.Bring a saucepan of water to a boil, add salt, and when water boils again, stir in pasta. Cook 3 mins, then drain and refresh under hot water.
5.Pour 300ml boiling water around meat in tray and spoon drained pasta evenly around.
6.Reduce oven temperature to 190 °C (170 °C fan-forced) and continue cooking lamb for a further 45 minutes for rare, or 60 minutes for medium rare.
7.During this time, stir pasta from time to time, and turn meat once. Transfer lamb to a heated serving dish and set aside for 10-15 minutes. Check seasoning of pasta mixture.
8.Spoon pasta around meat, then scatter with cheese, extra dried oregano and fresh oregano leaves. Carve lamb and serve with pasta and extra pecorino.