I got this simple tomato sauce recipe from Orangette. I made it to go with some pasta on a weeknight, and it was great. I used real butter and suffered no ill effects (though it was cultured butter, I should specify). It’s important to use the best-tasting canned tomatoes that you can find, but I’m not recommending a specific brand; they don’t have to be imported from Italy! This makes enough sauce for 4 servings of pasta.
2 cups whole, peeled, canned plum tomatoes, chopped, with their juices (about one 28-oz. can)
5 Tbsp unsalted butter
1 medium yellow onion, peeled and cut in half
salt, to taste
Combine the tomatoes, their juices, the butter and the onion halves in a medium saucepan. Add a pinch or two of salt. Place over medium heat and bring to a simmer. Cook, uncovered, at a very slow but steady simmer, adjusting the heat as necessary, for about 45 minutes, or until droplets of fat float free from the tomato. Stir occasionally, mashing any large pieces of tomato with the back of a wooden spoon. Taste and salt as needed.
Discard the onion before tossing the sauce with pasta.