This is an easy, delicious, and simple recipe from "Essentials of Classic Italian Cooking" by Marcella Hazan. You just mix all the ingredients on the stove and come back and hour later. The onions get meltingly soft and sweet. It'salso great with some crumbled blue cheese. If you use homemade pasta, which is more absorbent than spaghetti, you should start with 1 tbsp more butter when making the sauce. TO MAKE AHEAD : You can cook the sauce entirely in advance up to the point where you add the parsley. When you are nearly ready to toss with the pasta, reheat the sauce over medium heat and add the parsley just before draining the pasta.