The One Ingredient You Need To Easily Thicken Alfredo Sauce

So you've added butter into a pan and stirred in the heavy cream, minced garlic, and parmesan cheese. Now you're patiently waiting for your bubbling Alfredo sauce to thicken into gooey, velvety deliciousness before you toss it into a pot full of fettuccine, but alas — the sauce is a runny mess! Is there anything more disappointing than watching a rich Alfredo sauce turn into a watery white soup?

Fret not, though, for there is a very easy fix to this problem: All you need to do is add more cheese, which happens to be an excellent thickening agent. Simply grate the cheese or break it into little pieces, and add it to the sauce while it's still simmering on the stove. Begin by stirring in a small quantity of cheese, and then slowly sprinkle in more until the sauce thickens to your desired consistency.

Alfredo sauce is typically made using parmesan, so the best thing to do is to just add more of that. If that's not an option, other varieties such as Pecorino Romano (not to be confused with parmesan) and Grana Padano can work too. Just be sure to grate the cheese into really fine shavings using a microplane so that it melts quickly. That said, any shredded cheese can technically thicken a runny Alfredo sauce in a pinch, including cheddar. As long as it doesn't have too sharp a flavor that won't fare well in Alfredo sauce, you should be good to go.

While cheese is one of the best ways to thicken a watery Alfredo sauce, it is just one of several ingredients that can come to the rescue. The most obvious solutions are the ingredients that are already in your Alfredo sauce: butter and heavy cream. These ingredients, together with cheese, are what add that velvety richness to the sauce and help it cling to those starchy strands of pasta. Just stir in a pat or two of more butter, or add a splash of extra heavy cream to give the bubbling liquid some heft.

Often, the culprit behind a thin Alfredo sauce is simply the fact that the heavy cream wasn't reduced for long enough before the cheese was stirred in. Make sure to simmer the sauce until the cream has reduced by at least half (more if you want the sauce to be thicker) and only then sprinkle the cheese in. If it's too late for that, however, consider adding in some cream cheese or Greek yogurt to thicken the liquid. The only thing to bear in mind is that yogurt can curdle if it's added to a hot liquid, so always cool the Alfredo sauce before whisking it in. However, unlike cheese, cream, and butter, these two ingredients can subtly alter the flavor of your sauce, so take that into account before adding them.

Flour has a legendary reputation for being one of the best thickening agents. After all, it's flour that's mixed with fat to make a roux, which is then used as a base for creamy sauces like velouté and béchamel. So, when in doubt, simply make a roux, and then whisk it into the Alfredo sauce until it melts smoothly.

If that seems like too much of an effort, you can sprinkle a spoonful of flour directly into the sauce, or turn it into a slurry with water and then pour that in. Just make sure that there are no lumps of flour when doing so, and that you simmer the sauce until its powdery taste has been cooked through. Cornstarch is another excellent ingredient that can fix a runny Alfredo sauce, as is tapioca powder. Even just a dollop of mayo can add extra creaminess to an Alfredo sauce.

A clever way to thicken the cheesy sauce is also to stir in cooked and pureed vegetables — think cauliflower, squash, or potatoes. Not only will they give the sauce that much-needed creaminess, but they will also bulk up its nutritional value. They may have an impact on the flavor of the sauce as well, though not necessarily in a bad way. Alternatively, you can always just use the starchy water leftover from boiling pasta — after all, it's practically liquid gold for thick and creamy pasta sauces!