The Incredible Science-Backed Trick That Guarantees Perfect Cacio e Pepe Pasta Every Time

Cacio e pepe is one of those maddening dishes that seems so simple yet is so easy to mess up. In its truest form, it contains exceedingly few ingredients—pasta, Pecorino Romano cheese, black pepper, water, and salt—and when made properly, it is a beautiful expression of each. The cheese sauce is pure and sharp, but absolutely smooth and creamy; the black pepper is fragrant and supplies of spicy punch to back up the sharpness of the cheese; the pasta is the scaffolding that carries it all; and the water and salt play their respective roles to ensure the right sauce consistency and seasoning.

The hard part, of course, is making it properly. Pecorino Romano cheese is an aged cheese that’s dry and crumbly, which means it is just about the worst kind of cheese for melting. So much as look at it the wrong way when trying to melt it into the sauce and it will seize, separate, and clump into little stringy bits. There is no saving it once this happens. (There is still eating it, I’ve eaten plenty of my own failed attempts at cacio e pepe over the years and they still taste good even when the sauce is messed up.)

People have tried to come up with ways to stabilize the cacio e pepe sauce to prevent it from breaking, often to the chagrin of offended Italians. They add cream or butter, for instance, which provide an emulsified base into which the cheese can melt and dilute, reducing its propensity for breaking. But none of the resulting dishes taste quite like a true cacio e pepe, which has an austerity to it despite its richness—it is pure, liquified Pecorino Romano with black pepper. Cream and butter interfere with this purity, adding their own richness while diluting the intensity of the cheese.

It’s easy to make fun of Italians for being so wedded to their culinary traditions, casting them as adherents to tradition for tradition’s sake and fearful of innovation. That may be true sometimes, but more often the truth is that they understand their food deeply, and they recognize when “improvements” break the inherent character of a dish, as cream and butter do in a cacio e pepe.

But here’s the good news: There is an innovative way to make a cacio e pepe sauce that is much more resistant to breaking, and it avoids the pitfalls of the other methods, producing a silky sauce that tastes of Pecorino Romano cheese and black pepper and nothing else. With that plus a couple other careful steps, the result is phenomenal cacio e pepe, every time.

The Traditional Method of Making Cacio e Pepe

Cacio e pepe is one of Rome’s essential pasta dishes alongside classics like amatriciana, gricia, and carbonara. I’ve spent many a night trying to make perfect cacio e pepe using just the traditional method, and at this point I have a pretty high success rate. But it’s not 100%. I still have days when the sauce breaks on me, at times in inexplicable ways, suggesting that even subtle variations in the process can make the difference between success and failure.

Before explaining the innovative steps for making perfect cacio e pepe, it helps to review the basic traditional method. The following is one common method:

• Boil pasta.
• While the pasta boils, make a cheese paste with grated Pecorino Romano, black pepper, and some of the starchy pasta water.
• Transfer the boiled pasta to the cheese paste, thinning with additional pasta water as needed to produce a sauce that is creamy and emulsified, coating the pasty in a silky glaze.

Various things can create trouble during this process. Too much heat can cause the cheese to break, as can cheese that’s not grated finely enough. It’s a delicate dance to bring all the elements together successfully, ending up with a pasta that’s still hot enough to eat, cheese that has melted into the sauce, but not broken in the process.

The key to cacio e pepe that doesn’t break is to introduce an ingredient that can help stabilize the sauce without diluting it or introducing any unwanted flavors or textures. That ingredient is cornstarch, a common household ingredient we all usually have in our cabinets.

The Sauce Innovation: Cornstarch

It shouldn’t be a surprise that cornstarch has great powers when it comes to cheese sauce stabilization. It’s a common ingredient in other cheese sauces that are prone to breaking, like mac and cheese. In Kenji’s famous old recipe for stovetop mac and cheese, he uses cornstarch among other emulsifiers to make a sauce that’s like the boxed stuff, but better. The concept applies just as well here, and to be honest, I’m slapping myself for not realizing it long before.

This idea came to me much more recently when someone posted on the Serious Eats subreddit with a link to a science research paper titled Phase Behavior of Cacio and Pepe Sauce. In it, the scientists studied the effects of cheese coagulation as they related to both temperature and starch quantities, and developed and ideal ratio of cheese and cornstarch to yield a more bulletproof sauce.

I should note, this paper isn ‘t the first time the idea of using starch to stabilize cacio e pepe has been floated; first, the underlying concept of the sauce relies on the naturally starchy pasta water to play this role, though the quantity of starch is lower and highly variable depending on the quantities of both the pasta and the water and the brand of pasta itself. In recent years, both Ethan Chlebowski of Cook Well and Roman chef Luciano Monosilio have written and/or made videos about it. What the paper adds to the conversation is a deeper look at the physical processes that cause the cheese to break as well as a systematic testing of starch concentrations to hit a dialed-in sweet spot that isn’t too stiff from starch but still provides sufficient stabilization.

The reason this works has to do with why the cheese breaks in the first place. As the cheese is heated, the proteins in it bond with each other, squeezing tighter and tighter. As they squeeze, the fat that had been suspended in a stable emulsion is forced out, leading to stringy clumps and greasy oil. By introducing a cooked cornstarch gel, we’re able to increase the viscosity of the cheese mixture. On a molecular level, it can help to imagine the starch as a kind of interlocked network that gets in the way of the cheese proteins moving as freely, finding each other, and bonding tightly.

It’s an insurance policy that delivers fantastic results.

In practice, and with a couple small culinary techniques of my own, the process goes like this:

• Boil the pasta.
• While the pasta is boiling, dry-toast the black pepper in a small saucepan to develop its fragrance.
• Add a cornstarch slurry in a 1:10 ratio of starch to water by weight and cook it until the starch gels, forming a thickened, peppery gel.
• Let this gel cool slightly off heat, then mix it into the cheese to form a cheese-pepper paste.
• Use some of the pasta water to rinse out the cornstarch gel saucepan and add this to the cheese paste as well.
• Reserve some pasta water, then drain the pasta and let it cool slightly.
• Mix the pasta into the cheese paste, adding reserved pasta water as needed ot thin to a silky, creamy sauce.

The result will be perfect, every time.

Flavor Enhancement: Toasting the Pepper

This is one of those small details that isn’t essential, but helps make an even more flavorful dish. Toasting the black pepper develops its aromas and flavors, a process Nik Sharma has explained well for us before in his piece on South Asian tadka.

Heat … promotes two flavor-producing reactions: caramelization and the Maillard reaction. When sugars are heated, they undergo a series of chemical reactions that result in browning and new flavor molecules, which we identify as caramelization. The Maillard reaction refers to a series of reactions that involve the amino acids present in proteins and certain sugars (reducing sugars like glucose and fructose), but it also leads to browning and the development of new flavor substances. These reactions happen in foods of all sizes, not just onions or large cuts of meat. Even the essential oils inside spices are transformed chemically through oxidation during heating. The combined effect of these different transformations helps change the flavor profile of each of the individual ingredients…

Since we’re heating a pan to make the cornstarch gel anyway, we might as well toast the pepper in it first. That’s just smart cooking.

Key Technique: Managing Heat

One of the more subtle and difficult to control factors when making cacio e pepe is the heat. Make the classic sauce too hot, and it will definitely break. But let the ingredients cool off too much and you’ll be eating tepid cheesy pasta, which is not my idea of a good time,

When making cacio e pepe the traditional way, managing the heat properly is one of the most critical skills a cook can develop to ensure success. When making this version with cornstarch, we have a bit more leeway, though it’s still a good idea to be careful with the heat, allowing any component that is literally boiling hot to blow off just a little heat by letting it sit a minute or so before introducing it to the cheese sauce. This includes letting the cornstarch gel cool just a tad, as well as the drained pasta and the pasta water itself. Just make sure nothing cools too much, because you do want it hot.

On Cheese Grating and Blending

In the past, we’ve stressed the point that for a smoother cheese sauce, it’s helpful to grate the cheese more finely. In my own tests, I found that hard cheeses like Parm and Pecorino Romano melt less well than when they’re grated on a Microplane versus to a finer dust on the star-shaped side of an old-school box grater. The starch in this recipe makes this a somewhat less critical point, though it’s still helpful to grate the cheese as finely as you can.

The research paper itself recommends using a blender to process the cornstarch slurry and cheese to a paste, and you could do that instead, though I have had great success with this technique without doing that and would rather not dirty another piece of equipment if I can help it. If you do struggle to sufficiently blend the cheese and the cornstarch gel to form a thick paste, you can try using a blender as an aid.

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