Favorite (easy!) spaghetti sauce. Three ingredients! An Italian chef even confirmed that butter is totally a historical substitute for olive oil in this recipe.
500 g whole peeled tomatoes, canned (San Marzano, if you can find them)
70 g unsalted butter
1 medium-sized yellow onion, peeled and halved
Salt to taste
Cook 45 min. Mix pasta in sauce, top with grated Parmigiano-Reggiano. Next time I might use 2 x 500 g containers.
N.B. Meatballs in sauce are always served and eaten separately from pasta, in Italy.
EDIT: Apparently another classic is Marcella Hazan’s recipe