Tomato, Zucchini and Vidalia Galette

sheet frozen puff pastry, thawed

extra-virgin olive oil, divided

small Vidalia onions, thinly sliced

Salt and freshly ground pepper

tomatoes, stem ends trimmed

medium zucchini, ends trimmed

garlic-and-herb goat cheese, at room temperature

freshly grated Parmesan cheese

thinly sliced fresh basil leaves