HEAT 2 tablespoons of the oil in a frying pan over a medium heat and cook the onion for 6 minutes, stirring occasionally. ADD the garlic and anchovies and cook for a minute, stirring to break up the anchovies. ADD the chili, capers, olives, tomatoes, salt and pepper, and bring to the boil. REDUCE the heat to medium-low and simmer, uncovered, for 10 minutes, stirring occasionally. WHILE the sauce is simmering, cook the pasta. DRAIN the cooked pasta into a colander and put the sauce in the bottom of the pot. TOP with the hot pasta, parsley and reserved tablespoon of olive oil, and toss together gently to combine.