Marcella Hazan'S Famous Tomato Sauce, With Anchovies

• 28 ounces can crushed tomatoes, such as San Marzano or Bianco DiNapoli
• 3.3 ounces jar imported anchovy fillets in olive oil, chopped
• 5 tablespoons unsalted butter
• salt, to taste
• 1 medium yellow onion, peeled and cut in half
• 1 pound pasta, cooked, for serving (egg pappardelle noodles work well)
• freshly grated Parmigiano-Reggiano cheese, for serving

1. Stir the tomatoes, chopped anchovies, butter and salt (to taste) in a saucepan over medium heat. Add the onion and bring to a slow simmer. Reduce heat to sustain a bare simmer and cook, uncovered, for 45 minutes, carefully stirring around the onion every so often once the fat starts to float free from the sauce.
2. Discard the onion. Taste and correct for salt. Toss with pasta and serve with freshly grated Parmigiano-Reggiano cheese.

tomatoes, olive oil, unsalted butter, salt, yellow onion, pasta, cheese

Taken from food52.com/recipes/81048-marcella-hazan-s-famous-tomato-sauce-with-anchovies (may not work)