BraveTart's Ultimate Guide to Sous Vide Desserts

[Photograph: J. Kenji López-Alt]

Sous vide. Every time I hear the phrase, my upper lip twitches back in a half-formed snarl, then it takes a few calming breaths before I can trust my fingers on a keyboard. It's not that I've got a problem with the technique itself (who doesn't love a sack of wet meat?), my gripe is with the blind devotion that drives its most vocal acolytes to believe every recipe can be saved through baptism in a plastic bag.

I understand the appeal of a temperature-controlled water bath; that kind of precision is (hypothetically) a pastry chef's dream. I also understand that the closed environment prevents moisture loss, that the efficient transfer of gentle heat ensures uniform cooking from edge to center, and that the method takes all the guesswork out of timing, virtually eliminating the risk of under- or overcooking. And I certainly can't argue with its convenience as a make-ahead or bulk-cooking method.

When it comes to dead animals, whole eggs, and certain vegetables, there's a lot to love about a moist, low-heat, hands-off approach. But it's bonkers to think those conditions benefit every recipe, especially when you're not talking about a single item (a steak, an egg, a carrot), but rather the complex ecosystems of baking and pastry. Almost invariably, whenever I post a new recipe there are folks lined up to ask whether it can be cooked sous vide. Even when the recipe in question is a Hostess Donette.

Desserts need to expand, rise, evaporate, reduce, brown, crisp, and so many other things that just aren't going to happen in a steamy bag. Sure, a few sweet techniques are reasonably accomplished with sous vide, like tempering chocolate or culturing yogurt, but most everything else (poaching fruit, infusing cream) will only make sense if you're actively trying to avoid the stove, or if you don't have access to one in the first place.

So before you ask whether a perfectly innocent dessert could be sous vide-ified, pause to consider what it is that traditional methods mean to accomplish, then ask yourself whether or not that goal can be accomplished underwater. Spoiler alert: The answer is, generally, no. If you're not sure what the goal of traditional cooking methods are for a given dessert, that's a solid indication you're not equipped to successfully adapt a recipe to a fundamentally different cooking method. But if you can't shake the nagging curiosity, here are some questions to ask yourself before trying a dessert sous vide.

Would this recipe be better with the texture of a wet sock?

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[Photograph: Vicky Wasik]

Cakes, cookies, breads, doughnuts, and pastries are all leavened in part by steam. If the water content in a batter or dough isn't hot enough to achieve escape velocity, the result will be as dense, wet, and pale as a bowl of spotted dick. If you want a dessert that could be described as crispy, crunchy, flaky, or golden, steer clear of sous vide.

Along those lines, it's important to remember steam can emerge from the most unlikely of places. For example, the low heat of sous vide sounds fantastic for a batch of slow-roasted sugar, except that water is produced as a byproduct of its thermal decomposition. If not allowed to escape, that water will turn toasted sugar into a bag of grainy caramel. If you want caramelized sugar crystals to be powdery and dry, you need the dry heat of an oven.

Does the recipe mention stirring or whisking?

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[Photograph: Vicky Wasik]

The act of stirring or whisking something on the stovetop doesn't just promote even heat distribution; agitation disrupts coagulation. Consider, for a moment, the textural differences between a fried egg and a scrambled egg. By stirring, we break the egg into soft curds rather than allow it to form a solid sheet. Whether you're making the custard for Lemon Bars, Butterscotch Pudding, or even Swiss Meringue, stirring is integral to creating the fine, delicate texture we love in so many desserts.

Does it bubble or boil?

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[Photograph: Vicky Wasik]

Have you ever seen a recipe that calls for something to be simmered, boiled, or baked until bubbling hot? Welcome to the vast realm of Desserts You Shouldn't Ever Sous Vide. Reaching or surpassing 212°F is vital to both starch gelatinization and protein coagulation in dessert, and high heat is required to achieve caramelization and/or Maillard browning within any sort of reasonable time frame. That's a lot to take in, so let's look at each of those points in a little more detail.

At first blush, many starches seem to operate within a range compatible to sous vide. For example, tapioca can start thickening a liquid when heated to about 150°f, while cornstarch doesn't kick in until closer to 170°F. That's all fine and dandy until you factor in sugar, which elevates the temperature at which water can penetrate a starch granule. This effectively raises the gelatinization point of any given starch beyond what sous vide can achieve; for example, my cherry pie filling is thickened with tapioca starch but won't properly set until it hits 213°F.

Because sous vide cooking tops out at 210°F, the sugar saturation of any given mixture remains static from start to finish, making it impossible to cook even the simplest caramel sauce. Technically you could dissolve sugar in a bag of cream, but without surpassing 212°F it would never thicken over time, even if it did eventually caramelize.

While both caramelization and Maillard browning are hypothetically possible with sous vide, these reactions occur slowly enough to be practically impossible at temperatures below 212°F. Particularly in the realm of dairy centric desserts, the loss of Maillard browning means missing out on the toffee notes that develop with high-heat techniques.

Does the recipe involve eggs and sugar?

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[Photograph: J. Kenji Lopez-Alt]

We already know that sous vide is a fantastic cooking method for eggs, thanks to Kenji's carefully researched temperatures and timetables for soft-poached eggs, but sugar delays coagulation by a significant degree, throwing that data out the window. That's why cooking whole eggs to a mere 165°F will make a rubbery mess out of egg whites, but my Swiss meringue is still tender and soft even when baked to over 200°F.

Given the ratio of sugar to eggs in standard dessert formulations, sous vide cooking temperatures are often too low for proper coagulation, creating desserts that are too soft, loose, or gooey.

Are any of the ingredients more than 75% water?

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[Photograph: Vicky Wasik]

From milk, cream, and eggs to fresh strawberries, many of the ingredients in our favorite desserts are loaded with water that needs to be strategically removed through baking or boiling. So while it should be obvious something like homemade cajeta needs an open cooking vessel to reduce, many desserts benefit from evaporation in a far less obvious way.

My Swiss Meringue is a combination of egg whites and sugar cooked to 175°F over a water bath, which might sound ideal for sous vide if only you'd squish the bag from time to time to mimic stirring. The problem is that roughly an ounce of water will evaporate along the way in a meringue cooked over a water bath, which improves the meringue's stability and also extends its shelf life. That means the meringue won't collapse into a foamy film over your favorite layer cake when left out overnight, nor will it weep puddles into the bottom of your once crispy lemon meringue pie.

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[Photograph: Vicky Wasik]

The same is true even for oven baked custards like flan and creme brûlée, which traditionally start on the stovetop, where the dairy is first brought to a boil, then tempered into the eggs and cooked a bit more. Evaporation comes into play throughout that process, subtly but certainly reducing the custard's water content.

Does it go in the oven?

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[Photograph: Vicky Wasik]

People love cooking flan, creme brûlée, cheesecake, and even savory dishes like Eggs en Cocotte in sous vide baths because it's relatively foolproof compared to traditional methods, but that doesn't mean they turn out just as well. Baking in the dry heat of an oven rather than the moist heat of a sealed container allows for continued evaporation as well as Maillard browning along the surface, creating deeper overall flavor. In the case of creme brûlée, the comparatively dry skin that develops in an oven also allows the sugar layer to caramelize faster and more completely, with less risk of scrambling the custard below.

Have you answered yes to more than one question so far?

Any one of the previous issues might be overcome with the right technique, such as periodically squishing a bag or shaking a jar to simulate stirring, but when traditional cooking methods offer multiple benefits, you'll often only experience compounding problems with sous vide. Consider the pudding in my Chocolate Cream Pie. Evaporation concentrates and develops its flavor; stirring interferes with coagulation to create a silkier consistency; bubbling hot temperatures are required to gelatinize cornstarch; sustained boiling neutralizes a starch-dissolving protein found in egg yolks; Maillard browning deepens its toffee notes. In order for a dessert like that to work sous vide, the recipe would need to be reformulated from the ground up.

Did I personally give you the link to this article?

Then trust me, please, your dessert will be better off without sous vide.