Bring a large pot of lightly salted water to a boil. Boil the pasta until tender (see package for suggested cooking time).
Set a large skillet over medium heat and add the oil. Add the onion and garlic and cook and stir 2 to 3 minutes. Add the zucchini and cook 2 minutes more. Add the tomatoes and cook 3 to 4 minutes, or until softened. Stir in the basil, salt and pepper.
When the pasta is cooked, reserve 1/2 cup of its cooking liquid, and then drain the pasta well. Add the pasta and reserved cooking liquid to the skillet and toss to combine. Dish up and serve topped, if desired, with freshly grated parmesan cheese.