1. Bring a large saucepan of water to the boil, add salt and the pasta and cook until just al dente.
2. While the pasta is cooking, heat the oil in a pan.
3. Finely chop the garlic and rosemary, add salt and pepper to taste and fry over a medium heat for about 3 minutes, or until the garlic is barely golden.
4. Drain the pasta, keeping 3 tablespoons of the cooking water, and add both to the frying pan.
5. Saute, stirring continuously, for a couple of minutes, then arrange the pasta on a platter and serve very hot.