Marcella Hazan's Tomato Sauce with Onion and Butter

Ingredients:

1 large can San Marzano tomatoes
5 TBSP butter
1 medium onion, peeled and cut in half
Salt to taste
1/2 pound egg noodles (or pasta of your choice)
Freshly grated parmesan or parmiagano reggiano cheese

Simmer tomatoes, butter, onion and salt on low for 45.  Use the back of a spoon to break tomatoes down.  Serve over noodles with freshly grated parmesan or parmiagano reggiano cheese.