Tomato sauce (Marcella Hazan)

This recipe makes enough sauce for one pound of pasta. Scale up as needed.

Ingredients

2 cups tomatoes, with their juices (for example, a 28-ounce can of San Marzano whole peeled tomatoes)
5 tablespoons butter
1 onion, peeled and cut in half
Salt

Directions

Combine the tomatoes, their juices, the butter, and the onion halves in a saucepan. Add a pinch or two of salt.
Place over medium heat and bring to a simmer. Cook, uncovered, for about 45 minutes. Stir occasionally, mashing any large pieces of tomato with a spoon. Add salt as needed.
Discard the onion before tossing the sauce with pasta. (Note: these onions are delicious and can be eaten as a side dish or a chef's snack!)

Reference