Place tomato halves flesh side up and season with a generous helping of salt and pepper. Drizzle with 2 tbsp extra virgin olive oil and flip over. Throw on 3-4 cloves of garlic, then roast in the oven at 390F/200C for 25-30mins, or until the tomatoes begin to wilt and char. Roast at a lower temp for a longer period of time for a more intense, sweet flavour. Once cool enough to handle, squeeze out the garlic from the skins.
Add pasta to heavily salted boiling water and cook until al dente.
Meanwhile in a large pan over medium heat add 2 tbsp extra virgin olive oil. Add onion and fry until soft and beginning to brown. Add in 1/4 cup tomato puree/paste and fry it off for 1-2mins. Scrape everything into a blender and pour in the tomatoes & garlic (with the juices).
Pop the lid on, leave the hole at the top open and pop a clean tea towel over the top. Pulse until smooth, then add in basil leaves and pulse a little longer until they dice into small shards.
Pour sauce back into the pan and turn the heat to a low. Season with a pinch of salt and pepper (season well to bring out the best in this simple sauce), give it a stir for a couple of minutes to allow the air bubbles to burst, then start transferring the pasta straight from the pot into the sauce, using the excess pasta water it brings with it to emulsify the sauce. Toss the pasta to coat, using a dash more starchy pasta water if needed to bring everything together.
Sprinkle over parmesan and give it one final toss. Serve individual portions with another sprinkling of parmesan and a drizzle of extra virgin olive oil.