1 tablespoon olive oil
1 yellow onion, thinly sliced
4-6 garlic cloves, thinly sliced
3 tablespoons tomato paste
1/2 teaspoon crushed red pepper, plus more for serving
16-20 oz cherry tomatoes, halved
2 tablespoons basil, chopped, optional
1 oz parmesan, grated, optional
1 tablespoon butter, optional
- Bring a large pot of generously salted water to a boil.
- To a high sided skillet on medium-high heat, add the olive oil and onions. Sauté the onions until they’re translucent and beginning to brown around the edges, about 5-7 minutes.
- Add the garlic, tomato paste, and crushed red pepper, and stir to coat the onions and garlic in tomato paste. Cook until the tomato paste turns a deep shade of red, about 3-5 minutes. Add the heirloom cherry tomatoes, season with a generous amount of kosher salt, and stir. Cook, stirring often, until the tomatoes begin to release their juices, about 5 minutes. Add 1 cup of water, and bring to a heavy simmer, stirring occasionally, until the sauce has reduced and the flavors have come together .
- In the meantime, add the spaghetti and cook for 1 minute less than suggested by the package, usually around 9 minutes.
- Transfer the pasta straight into the sauce and toss to coat, using pasta water as needed to loosen the sauce.
- Remove from the heat. Optionally, add the fresh basil, parmesan, and butter and toss to coat.
- Serve with more basil, parmesan, and crushed red pepper flakes.