Ingredients :

• The cream — Full-fat cream, 30-35% fat content — known as heavy cream or whipping cream. Light cream results in a thinner sauce that slides off the pasta instead of coating it. There’s no real substitute here if you want that silky texture.
• The parmesan — Grate it yourself, fresh. Pre-shredded bagged parmesan contains anti-caking agents that prevent the sauce from binding — you’ll end up with little white lumps instead of a velvety sauce.
• The asparagus — Choose medium stalks. Too thin, they cook in seconds and disappear into the sauce. Too thick, they stay fibrous. To remove the woody end, snap the stalk by hand — it breaks naturally at exactly the right spot.
• The pasta — A shape with nooks and crannies to catch the sauce: penne, rotini, farfalle. Spaghetti doesn’t work well here — the sauce slides off. Mafalda, with its wavy edges, is perfect if you can find it.