From America's Test Kitchen Season 11: Simply Italian
With just three main ingredients (cheese, pepper, and pasta), this Roman dish makes a delicious and quick pantry supper. But in versions we tried, the creamy sauce quickly turns into clumps of solidified cheese. We wanted a sauce that was intensely cheesy but also creamy and smooth.
Our science editor explained why the cheese clumps in this dish. Cheese consists mainly of three basic substances: fat, protein, and water. When a hard cheese like Pecorino, our cheese of choice, is heated, its fat begins to melt and its proteins soften. The fat acts as a sort of glue, fusing the proteins together. In order to coat the cheese and prevent the proteins from sticking together, we needed to introduce a starch into the mix.
It occurred to us that as pasta cooks, it releases starch into the water. We reduced the amount of water to concentrate the starch and whisked some of the cooking liquid into the cheese. This helped to a point, but we found we also needed an emulsifier—something to bind together the sauce. We turned to cream. By switching the butter for cream, we created a light, perfectly smooth sauce that had all the cheese flavor we wanted. Even after sitting on a table for a full five minutes, there wasn’t a clump in sight.
Serves 4 to 6
High-quality ingredients are essential in this dish, most importantly, imported Pecorino Romano—not the bland domestic cheese labeled “Romano.” Use the small holes on a box grater to grate the cheese finely and the large holes to grate it coarsely. Alternatively, a food processor may be used to grate it finely: Cut the Pecorino into 2-inch pieces and process until finely ground, about 45 seconds. For a slightly less rich dish, substitute half-and-half for the heavy cream. Do not adjust the amount of water for cooking the pasta. Stir the pasta frequently while cooking so that it doesn’t stick to the pot. Letting the dish rest briefly before serving allows the flavors to develop and the sauce to thicken.