Preheat and prep: Heat your oven to 425°F (220°C). Line a large sheet pan with parchment for easy cleanup. Cut larger tomatoes in half; leave cherry tomatoes whole. Slice the onion. Keep the garlic cloves in their papery skins so they don’t burn.

Toss with oil and seasoning: Spread tomatoes, onion, and garlic on the sheet pan. Drizzle with olive oil and season with salt, pepper, oregano, and red pepper flakes. Toss to coat and spread in an even layer.

Roast until caramelized: Roast for 25–35 minutes, stirring once. You’re looking for blistered edges, collapsed tomatoes, and soft onions. The garlic should be tender when pressed.

Squeeze the garlic: Let everything cool for a few minutes. Squeeze the roasted garlic from the skins into a bowl or directly into a pot. Discard the skins.

Blend or crush: Transfer the roasted vegetables and released juices to a blender or food processor. Add the tomato paste if using. Blend until smooth for a classic sauce, or pulse a few times for a chunky texture. Alternatively, tip everything into a pot and use a potato masher for a rustic finish.

Simmer and balance: Pour the sauce into a medium pot and bring to a gentle simmer. Add vinegar to brighten, then taste. Adjust salt and pepper. If your tomatoes are very acidic, add a tiny pinch of sugar. Simmer for 10–15 minutes to meld flavors.

Finish with basil and oil: Stir in torn basil leaves and a drizzle of olive oil for sheen and flavor. Keep warm over low heat.

Cook the pasta: Boil pasta in well-salted water until al dente. Reserve 1/2 cup pasta water.

Toss and serve: Add drained pasta to the sauce, loosening with splashes of pasta water as needed to help the sauce cling. Finish with grated Parmesan and more basil if you like. Serve hot.