1. In a medium sized saucepan, heat the olive oil over medium heat. Add the onions and cook, stirring occasionally, until they begin to soften, about 5 minutes. Add the garlic and cook for 1 more minute.
2. Add the tomatoes, bring to a simmer, cover and cook for 30 minutes, stirring once in a while.
3. Add the basil, sugar, salt and pepper and simmer, uncovered, until the sauce thickens, about 15 minutes more. Adjust the salt and pepper.
4. Meanwhile, bring a large pot of salted water to a boil. Add the fettuccine and cook until it is al dente, about 8 to 10 minutes. Drain.
5. Return the pasta to the pot it was cooked in and toss it with the tomato-basil sauce. Divide the pasta among 4 serving bowls, sprinkle with Parmesan cheese, garnish with fresh basil leaves, and serve immedieately.Serving Size: 1 bowl with sauce