Pasta risottata in salsa

I owe this recipe to Nigella Lawson, who, in her excellent book Nigellissima, brought this method of cooking pasta to my mind. Years ago, when we were staying in a B & B high up in the wilderness of the Calabrian mountains, I had a plate of ditalini floating in a red sauce speckled with brown bits and green blobs. It looked and tasted a little different from the usual pasta, so I asked the sig