For the tuna spaghetti, first cook the spaghetti in salted water. Sauté the onion, garlic and finely chopped chili pepper in olive oil, add the tomato pieces. Then add the finely chopped anchovy fillets and parsley. Lightly salt and simmer for about 2 minutes.
Then add the chopped tuna and the chopped capers. If the sauce is too thick, you can add some of the pasta water. Add a dollop of whipped cream if desired. Mix the tuna spaghetti in the pan.