1medium-size10-ounce yellow onion, peeled and cut in half lengthwise
5tablespoonsunsalted butter2 1/2 ounces
1teaspoonkosher saltplus more to taste
1lbdried pasta
Instructions
Place tomatoes in a medium saucepan
Add onion
Stir in butter and salt.
Cook over medium-low, uncovered, stirring occasionally and mashing any large pieces of tomato using the back of a wooden spoon, until fat floats free from the tomatoes and is incorporated into the sauce as it slightly thickens, 1 hour to 1 hour and 10 minutes.
Season with additional salt to taste. Remove and discard onion. Toss with cooked pasta.