Bring a large pot of salted water to boil and prepare a large bowl with ice water. Score the stem end of the tomatoes with and "x" and plunge them into the boiling water for 10-15 seconds to loosen the skins (do not drain the water, which will be used for cooking the pasta).
Transfer them to the ice bath to rapidly cool, then slip off the skins, deseed, and chop the flesh.
In a large saucepan, heat the olive oil over medium heat until shimming, then add the tomatoes. Cook over medium heat until the tomatoes are significantly broken down and soft, 20-25 minutes.
Add the onion and garlic to the pan and continue simmering unit the onion is soft. Season to taste with salt and pepper. Stir in most of the basil.
In the meantime, cook the pasta in the boiling water until al dente. Reserve 1 cup of pasta cooking water before draining.
Add the pasta to the tomato sauce and toss well with tongs to combine. Taste and adjust the seasonings and transfer to serving plates. Top with the remaining basil and a drizzle of olive oil and serve.