From http://inthekitchenwithkath.com
(Adapted from the recipes in Marcella Hazan's Essentials of Classic Italian Cooking and Giuliano Hazan's The Classic Pasta Cookbook)
Makes enough to sauce a pound of pasta
Serves 4 – 5 as a main course, 6 – 8 as a first course or side dish
2 pounds of peeled and seeded plum tomatoes, or 1 (28 oz) can of peeled canned tomatoes, with their juice
5 - 6 tablespoons butter (Marcella calls for 5; Giuliano uses 6. I usually use 6.)
1 medium-sized onion, peeled and cut in half
Salt to taste (you won’t need much with canned tomatoes)
1. Cut the tomatoes into small pieces (Canned tomatoes are easily cut right in the pot with kitchen scissors.)
2. Put everything in a pan and simmer, uncovered, over low heat. Cook for about 45 minutes, until the tomatoes are reduced and you can see that the butter has separated out.
3. Remove the onion halves and discard. (Or enjoy eating them, as Bob did.) Toss the sauce with hot pasta and serve with Parmesan cheese to grate at the table.