- 3 tablespoons unsalted butter
- 4 tablespoons olive oil
- 1 ½ thinly sliced medium red Onion
- 1 ½ cup canned tomatoes, crushed in their own juices
- 1 lb spaghetti
- coarse salt to taste
- 4 tablespoons Parmesan cheese, grated
Melt some butter and heat some oil in a heavy pan over medium-low heat. Add the onion and sauté. Once you know from the smell and the color that the onion is ready-not brown, but translucent, soft and golden-stir in the tomatoes, Let the mixture cook slowly, uncovered, until the liquid is gone, but do not over-reduce.
Meanwhile, cook the spaghetti in boiling salted water until al dente. Reserve some of the cooking liquid in a heatproof container, then drain the pasta.
When the sauce is ready, stir in a little more butter to enrich and thicken it. Add the pasta to the pan, and toss. If the dish seems dry or the sauce isn’t quite bound, add a tablespoon or so of cooking liquid and toss again. Add Parmesan, toss some more and serve