Arrabbiata sauce is traditionally served with penne and topped with grated pecorino. For more variety, add shrimp or serve with mussels. Average proportions are 375 mL (1 ½ cup) tomato sauce for 500 g (1 lb) pasta. Don't throw away all your pasta cooking water: it's a good idea to add a bit to your sauce. Mix in ¼ to ½ cup (or a ladleful) cooking water with the sauce before adding the pasta. The salted, starchy water will enhance flavours and thicken the sauce, helping it stick to the pasta.