Lazio — cacio e pepe is the most ancient of the Roman pasta preparations, predating the tomato. The name is the recipe. It is the pasta of the transhumance shepherds (the cacio from the Abruzzo sheep, the pepper from the Roman spice trade), and it is the preparation that most purely tests the cook's ability to emulsify cheese.
Cacio e pepe is the most demanding technically of the Roman pasta preparations — three ingredients (pasta, Pecorino Romano, black pepper), no fat added, no cream, and the cheese must be emulsified into the pasta water to create a silky, sauce-like consistency that coats every strand without becoming glue or clumping. The preparation is ancient (the Roman shepherd's pasta, made with the hard sheep cheese carried in the pack and the black pepper from the spice trade) and requires a specific technique to achieve the correct emulsion. The failure mode is either clumped, stringy cheese or a watery pasta with no sauce. The success condition is a pasta where the cheese has become an invisible, silky coating.
Perfect cacio e pepe in the bowl is a study in apparent simplicity — the tonnarelli coated in a pale, silky cheese glaze with the black pepper clearly visible and fragrant. The Pecorino Romano is pungent, sharp, and slightly salty; the black pepper adds heat and aroma. There is nothing else. Achieving the correct emulsion — silky, not clumped — is the entire challenge. When correct, it is one of the most satisfying pasta preparations in existence.
Pasta: traditionally tonnarelli (square-cut spaghetti) or spaghetti. Cook pasta in heavily salted, abundant water. In a large bowl or wide pan, mix very finely grated Pecorino Romano (aged 12+ months — the most pungent variety) with a small amount of very cold pasta water to form a smooth paste. Toast black pepper generously in a dry pan until fragrant. Drain pasta with significant pasta water retained. Add drained pasta to the pan (off heat); toss 10 seconds with a small amount of pasta water. Off heat, add the Pecorino paste; toss vigorously — the residual heat of the pasta melts the cheese; the starch in the pasta water prevents it from clumping. Add more pasta water drop by drop if needed for consistency.
The Pecorino Romano must be the most aged, most pungent version available — younger Pecorino or Parmigiano is not correct for cacio e pepe. The pasta water temperature is the critical variable — it must be hot enough to melt the cheese but not so hot that it causes the protein to denature and clump. Some chefs add a small amount of rendered lard or guanciale fat — a compromise with the strict three-ingredient version. The technique is best learned by watching an experienced cook perform it.
Pecorino paste added to pasta that is too hot — if the pasta is still steaming aggressively, the cheese clumps; the pasta must be slightly cooled before adding the cheese paste. Insufficient pasta water retained — the starch in the pasta water is the emulsifying agent; without it, the cheese seizes. Coarsely grated Pecorino — very fine grating is essential for the cheese to dissolve into the sauce; medium grating produces lumps.
Giorgio Locatelli, Made in Italy; Anna Gosetti della Salda, Le Ricette Regionali Italiane