Serves 4 to 6

This dish will be very warm, not hot. The success of this recipe depends on high-quality ingredients, including ripe, in-season tomatoes and a fruity olive oil (the test kitchen prefers Columela Extra-Virgin). Don’t skip the step of freezing the mozzarella, as freezing prevents it from turning chewy when it comes in contact with the hot pasta. If handmade buffalo- or cow’s-milk mozzarella is available (it’s commonly found in gourmet and cheese shops packed in water), we highly recommend using it, but skip the step of freezing and add it to the tomatoes while marinating. Additional lemon juice or up to 1 teaspoon sugar can be added at the end to taste, depending on the ripeness of the tomatoes.

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.

WHY THIS RECIPE WORKS:
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

Serves 4 to 6

For tips on trimming asparagus, see related tip. Campanelle is our pasta of choice in this dish, but farfalle and penne are acceptable substitutes.

Serves 12

One cup of plain yogurt thinned with ½ cup milk can be substituted for the buttermilk. Grate the onion on the large holes of a box grater. The ingredients in this recipe can be reduced by two-thirds to serve 4. For instructions on how to cook the pasta in less water, see Lots of Pasta, Less Water (related).

Serves 4 to 6

Let the dish rest briefly before serving so the flavors develop and the sauce thickens.

Serves 8 to 10

We prefer the lasagna made with our favorite wholemilk, block-style mozzarella from Sorrento, but Kraft part-skim preshredded mozzarella is also fine. Our preferred brands of crushed tomato are Tuttorosso and Muir Glen.

Serves 2 to 3 as a main dish, or 4 to 6 as an appetizer

For the most accurate measurements, weigh the potatoes and flour. After processing, you may have slightly more than the 3 cups (16 ounces) of potatoes recquired for this recipe. Discard any extra or set aside for another use. Besides the browned butter sauce, try our Gorgonzola Cream Sauce, Parmesan Sauce with Pancetta and Walnuts, and Porcini Mushroom Broth (related).