It's Marcella Hazan's onion-butter-tomato sauce.
And it's not just me who thinks so. No one who has tried this sauce doesn't agree. The beauty part is that it's dead easy, super tasty, and freezes wonderfully.
Make it. Make it now. Seriously.
Here's what you need:
big can of whole tomatoes (though I've fudged it with a big can of chopped tomatoes)
Half a stick of butter
A yellow onion
Open the can of tomatoes, dump it into the saucepan. Break them up a bit with your (clean) hands or a wooden spoon. Add half a stick of butter (per can of tomatoes, you can double this recipe super easily). Cut the onion in half, and take off the peel and any root thingies. If your onion is small, throw in both halves as is. If it's big, throw in one half, and stick the other half in the fridge for something else. Add a big pinch of salt, and put the pot on low heat.
The butter will melt into the tomatoes and disappear. about 30 minutes later, the butter will start reappearing as little droplets of oil on the surface. Fish out the onion and toss it. Stir, breaking up the tomatoes a bit more if you need to.
It's like crack, right?. SO GOOD.