What Is Pastry Cream?
The universe of custards is large and varied. There are pourable custards like crème anglaise, which essentially function as a sauce for desserts and rely solely on the thickening power of eggs; there are baked custards like flan, which also use eggs as their thickener, but in a high enough proportion that they set more solidly; and there are stiff custards like pastry cream, which combine the thickening powers of eggs and starch to create a substance that can be piped or spread and will retain its shape.
At its most basic, pastry cream is a combination of milk, eggs, and starch that are cooked together to create a rich and thick custard that’s a workhorse in the baker’s kitchen. One batch of chilled pastry cream has many uses: It can be piped into cream puffs and éclairs, spread on layers of puff pastry for a mille-feuille, or used as the filling in fruit tarts, cakes (think Boston cream pie!), and even donuts. Furthermore, it serves as the base of several more advanced creams: lightening it with whipped cream makes crème légère, combining it with meringue yields crème chiboust, and mixing it with whipped butter results in crème mousseline.
Let’s take a closer look at the main ingredients; each plays an important role in making a successful pastry cream.
Milk
The choice of milk affects a pastry cream’s flavor, body, and texture. I tested whole milk (which is the go-to in the majority of pastry cream recipes) against skim milk, half and half, and heavy cream, and found that there’s a good reason why whole milk is the most common. It delivers a full body, rich flavor, and an unrivaled smooth and creamy texture.
The other three couldn’t compete: skim milk was lacking in flavor and loose in texture; half and half was too firm, with an off-putting buttery taste; and heavy cream separated during the cooking process (the fat leeched out, turning the mixture into a greasy mess). I recommend sticking with whole milk for optimal results.
Eggs
Eggs contribute flavor and provide structure to pastry cream. Pastry cream typically calls for egg yolks, not whole eggs or whites, since, due to their higher fat content, yolks supply a fuller flavor, a richer color, and a tender, more creamy structure. Replacing yolks with whole eggs or whites results in a cream that’s less flavorful and more loose in texture.
What was more difficult to pinpoint was the optimal number of egg yolks per recipe. Most recipes follow a rough guideline of four to six yolks for every two cups of whole milk. My tests with four egg yolks delivered the ideal texture—one that’s stiff and can hold its shape without flowing, but not too firm or heavy. That said, if you want a thicker cream with an eggier flavor, feel free to add up to six egg yolks per two cups of milk.
Starch
Starch thickens pastry cream. Most recipes incorporate flour, cornstarch, or a mix of the two. I found that flour produced a thicker, heavier texture and imparted an undesirable “floury” taste. Cornstarch, on the other hand, delivered the goods—it had a bright, clean taste that didn’t mask the flavor of the dairy and flavorings, plus it’s gluten-free (in case that’s a plus for you). Root starches, like potato and tapioca, did not work well at all, producing a jello-like pastry cream with a stringy texture (meaning I could feel starchy strands in my mouth).
Sugar
Sugar is required in a pastry cream for the sweetness it brings, but it has another important role: it helps slow down the rate at which the eggs coagulate, allowing the pastry cream to be cooked sufficiently with a lower risk that the yolks will scramble. Similar to eggs, it was tricky to nail down the optimal amount. A majority of recipes add between one-quarter cup to two-thirds cup for every two cups of milk. I roughly split the difference and found that a half cup delivered the perfect level of sweetness—one that was rich without being tooth-achingly sweet.
Applying Heat: The Critical Steps for Thickening Pastry Cream
Heating milk, eggs, cornstarch, and sugar on a stovetop while whisking to make pastry cream
Serious Eats / Vicky Wasik
The success or failure of pastry cream hinges on sufficiently heating the custard base. The goal is to properly thicken the custard to achieve a consistency that is stiff, thick, and smooth, while remaining easy to pipe or spread. If the resulting pastry cream is too runny and loose, or overcooked and gritty, then we either fell short or overshot this essential step in the process.
Pastry cream relies on two thickeners—the starch and the eggs—working in tandem to thicken the custard. The steady application of heat serves as the catalyst for the processes of gelatinization for the starch and coagulation for the eggs.
When mixed with water (provided by the milk in this case) and heated to around 175°F, starch granules gelatinize, meaning they absorb and swell up with water, then leak out their starchy molecules, effectively thickening the custard base. While all of this is happening, the proteins in the yolks are denaturing, or unfolding and then coagulating, or bonding together, to form a strong, flexible network.
If gelatinization and coagulation were our only concerns, we could bring the pastry cream to 175°F and be done. Unfortunately, the yolks contain an enzyme called amylase, which can slowly break down the starch molecules and transform thick pastry cream into a runny sauce. The solution to this problem requires getting the pastry cream even hotter—to what we might describe as a “bubble,” with the mixture at a temperature just shy of boiling. Holding the pastry cream at a bubble while whisking constantly for about a minute or so deactivates the amylase so that it’s no longer a threat to the structure of the pastry cream.
Getting the egg-containing custard so hot may sound like we’d risk immediately scrambling the eggs, but several factors are on our side to prevent that from happening. First, the milk dilutes the egg proteins, so they’re farther apart and less likely to rapidly and tightly bond. On top of that, both the starch and the sugar run additional interference to prevent the egg proteins from bonding. This means you can safely bring the pastry cream to a near boil while whisking for at least a minute without it overcooking.
And that brings me to one more very important point: I can’t emphasize enough the need for constant attention and whisking. If you’re a multitasker in the kitchen, it’s best to set other tasks aside and focus all of your attention on the pastry cream. Don’t walk away or check your phone, and be sure to whisk, whisk, whisk. Whisking ensures that the pastry cream is evenly thickened and reduces the chance for lumps and scorched spots to develop.
What About Tempering?
tempering milk into egg, sugar, and cornstarch mixture
Serious Eats / Vicky Wasik
When making the custard base, almost all pastry cream recipes reflexively call for tempering, which involves whisking hot milk into eggs to reduce the chances of ending up with scrambled eggs (keep in mind that this happens before the pastry cream is cooked to thicken it).
But you don’t always need to temper when making pastry cream. It’s only necessary if the milk needs to be heated first. For example, if you want to flavor the pastry cream by infusing the milk with something like the vanilla bean in this recipe, or the lemon zest in my lemon pastry cream, then tempering is necessary because the milk will have been heated during the infusion step.
However, if there’s no reason to preheat the milk, it’s perfectly okay to simply combine all of the pastry cream’s ingredients while cold and heat them up together. For instance, in my chocolate pastry cream recipe, the pastry cream base is made without a tempering step, and then the chocolate is melted into the thickened custard while it’s still warm.
You can read more about the ins and outs of the tempering process in our article on the technique, but rest assured, we at Serious Eats will only ask you to go through that added step when it makes sense.
How to Add to Flavor to Pastry Cream
A vanilla bean being removed from a pot of milk after steeping
Serious Eats / Vicky Wasik
I’ve cooked up countless batches of pastry creams, in the pursuit not only of a rock-solid basic recipe like the vanilla pastry cream below, but also of guidance on how to create any number of flavor variations. My small group of taste testers, consisting of my husband and our toddler, tried ones flavored with fresh mint, chocolate, sesame oil, peanut butter, and lemon, to name a few. Some were hits, others flopped, but all were useful, in that they led me to devise the following guidelines for how to best go about adding flavor:
Milk Infusions: To extract maximum flavor from dry and vegetal ingredients like spices, teas, herbs, coffee, ginger, and zests, I recommend infusing the milk with the ingredient first. Combine the milk and flavoring ingredient in a pot, bring the mixture to a bare simmer, then let it steep, covered, for as little as a few minutes and up to 1 hour, depending on the ingredient. You can then strain out larger ingredients as needed, or in the case of finely grated citrus zest or vanilla seeds, leave them in. If the milk is still hot when the infusion is complete, you will need to temper the eggs with it to prevent scrambling, which I call for in the vanilla pastry cream recipe below and in the lemon pastry cream (depending on the duration of the infusion, the milk will cool to varying degrees, so the key is to always temper if you have any concern it might still be too hot).
Wet Stir-Ins: Honey, maple syrup, pomegranate molasses, citrus juice, jam, and flavored oils like sesame and olive oil, are all fantastic options. To account for the extra liquid, you will often need to slightly increase the amount of cornstarch and egg yolks in order to achieve a final consistency that’s thick enough. In most cases, wet stir-ins should be whisked in only after the finished pastry cream has chilled, since many can interfere with it setting properly if added earlier.
Dry Stir-Ins: You can approach this category in one of two ways, either initially combining the stir-in with the rest of your dry ingredients or whisking it in off-heat once the pastry cream has properly thickened. The former works well for ground spices and cocoa powder, while the latter is ideal for chopped chocolate, which will melt in the hot pastry cream.
Pastes: Once the pastry cream has been removed from the heat, you can stir in pastes, such as peanut butter, pistachio paste, Nutella, and tahini paste. Keep in mind that adding any unsweetened paste, even in small quantities, will reduce the overall sweetness of the cream; you’ll need to compensate for this by increasing the amount of sugar. In addition, there’s no need to worry if you are stirring in a particularly thick paste; it will easily dissolve into the hot pastry cream.
Once you’ve become confident with adding individual flavorings, it’s fun to experiment by building more complex flavor combinations. For instance, pairing chocolate and mint in a pastry cream can easily be accomplished by steeping fresh mint in milk, then whisking in chocolate off-heat. There’s a lot of flexibility here, and I encourage you to play around. If you need inspiration, a book I find myself reaching for over and over again is The Flavor Thesaurus, which offers a framework for flavor pairings.
Can You Sous Vide Pastry Cream?
The answer is…undetermined. Knowing this would be a popular question (plus, I was curious too), I dug up a few recipes that claimed to produce pastry cream using an immersion circulator. The one I found omitted the starch and instead relied on a much higher number of egg yolks, the idea being that with such precise temperature control, one could cook the yolks until just firm enough but not hard or chalky, which would serve as an effective thickener when blended with the rest of the ingredients. The curdled soup the recipe produced was a disaster.
I tinkered around with the process, but didn’t manage to get it to a place where the flavor or texture were appealing. I don’t want to say it’s impossible—maybe with more testing there’s a way to make it work, but I haven’t found it yet.
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