Marcella Hazan's 3-ingredient pasta sauce has been blogged about, pinned, and shared on Facebook dozens of times. While it's delicious and incredibly simple, the sauce is a bit to thin for my taste. It does, however, make for the perfect tomato soup.
When the sauce is done, remove the onion and use an immersion blender to smooth it out. Top with a tablespoon of shredded cheese (I used cheddar, but with a bit of basil and a slice of bread, Parmesan would be perfection). Place under the broiler until it's melted and bubbly.
The original recipe calls for salt, but I never add it. I find that the canned tomatoes are salty enough.