This sauce is made with a little minced garlic, white onion, a 1/2 teaspoon fresh red chilies and anchovies which are sauteed in olive oil until the anchovies are dissolved. Then add diced tomatoes and cook until the tomatoes are very soft for 15 to 20 minutes . Then add , olives and some capers.
Cook the tagliatelle in salted boiling water until al dente, drain and tip the pasta into the tomato sauce. Add some of the pasta water and toss the pasta with the sauce and cook for about 3 or 4 minutes. Sprinkle with some chopped parsley and some grated Parmesan. Serve immediately.