In a large saucepan combine crushed tomatoes, diced tomatoes, tomato puree, minced garlic, sugar, parsley, garlic powder, salt, oregano, basil and ground black pepper. Add capers and crushed chilli flakes if desired. Cover. Bring to a boil.
Lower heat and simmer for 45 to 60 minutes.
As simmering time nears, in a large pot with boiling salted water cook spaghetti until al dente.