Why It Works
- Using toasted sugar brings the overall sweetness into balance, adding complexity of flavor.
- Liquid ingredients help the sugar dissolve and add a note of flavor.
- At 155°F (68°C), the egg yolks will be fully cooked.
- Testing the finished buttercream with a thermometer helps rule out problems related to temperature, a common concern in recipes built on butter.
Most bakers are familiar with meringue-based buttercreams, like Swiss and Italian, but their French cousin isn't nearly as well known. In part, that's because Swiss and Italian buttercreams are cheap and practical, turning leftover egg whites into something useful and delicious—frosting for cake.
French buttercream, on the other hand, is made from whipped egg yolks, and egg yolks have many other, more popular uses: vanilla custard, lemon curd, chocolate pudding, or even yellow cake. It's not often that home bakers have a dozen egg yolks to spare, but it's been known to happen—in the aftermath of making angel food cake or macarons, for example. But French buttercream is also insanely delicious, with a rich custard flavor like the best vanilla ice cream, so it's worth having a recipe up your sleeve, or at least on your radar.
A Water Bath Eliminates Risk and Mess
Classically, French buttercream is made by pouring a hot syrup over whipped egg yolks, but I make mine over a water bath instead. It's a method similar to my technique for Swiss buttercream, one that eliminates the mess (and risks) associated with pouring a boiling sugar syrup into a running mixer. It's also a method that ensures those egg yolks are fully cooked, something that can't be said for traditional French buttercream.
The first step is to combine the egg yolks with sugar, salt, brandy, and vanilla. The brandy could just as easily be bourbon, rum, or even water—anything liquid to help loosen the thick yolks. I like brandy best, because it's flavorful and aromatic but subtle, adding depth of flavor to the buttercream without getting in the way.
The mixture is set over a steaming water bath and stirred constantly with a flexible spatula until it hits 155°F (68°C). This temperature ensures that the sweetened egg yolks are fully cooked, as sugar will alter their normal cooking temperature.
When the mixture comes to temperature, it transforms from a thick and grainy paste into something almost like a syrup, smooth and loose, but thick.
Using a Stand Mixer
Immediately transfer it to a stand mixer, and whip on the highest speed until the egg yolk mixture is thick, foamy, and just beginning to ball up on a whisk. This takes about eight minutes on my KitchenAid, but the exact timing can vary considerably with the wattage of your mixer, so let the visual cues be your guide.
Once the egg yolks are fluffy, begin adding cool butter a few chunks at a time. The egg mixture is typically around 90°F (32°C) at this time, so I like to use 65°F (18°C) butter, but there's a lot of wiggle room when it comes to temperature—so long as the two average out to something in the 70s°F (20s°C).
The mixture may look a little strange at first, but as the butter is incorporated, it will eventually become glossy, smooth, and thick enough to hold stiff peaks.
Troubleshooting the Texture
Buttercream is the least mysterious recipe to troubleshoot. If it's soupy or thin, it's too hot. If it's curdled or greasy, it's too cold. Either problem is easily solved by warming or cooling the buttercream, so there's never any reason to panic or despair. If your buttercream isn't the perfect consistency for spreading over a cake, just follow my troubleshooting guide for Swiss buttercream. French buttercream may start with different ingredients, but its backbone is still butter, so it can be fixed in exactly the same way.
Properly made, French buttercream should weigh about six and a quarter ounces per cup. If yours turns out even lighter, that's fantastic, but if it's significantly denser, that's a sure sign the buttercream was too cold to be properly whipped. Again, this is easily remedied by warming and re-whipping the buttercream, per the troubleshooting guide.
Once it's been whipped to the perfect consistency, French buttercream is light and silky, with a dreamy, melt-in-your-mouth texture. It's wonderful as is, but also easily customized with ingredients like melted chocolate, peanut butter, ground nuts, or spices—with cinnamon and nutmeg to play off the brandy, it's also the perfect eggnog-flavored frosting. Pair it with anything from classic vanilla butter cake to chocolate cherry cake, or even a carrot cake for those who aren't keen on cream cheese frosting.
5 1/2 ounces egg yolk (shy 2/3 cup; 155g), from about 10 large eggs
5 1/4 ounces plain or lightly toasted sugar (about 3/4 cup; 145g); (see notes)
1 ounce bourbon, brandy, rum, tea, or coffee (about 2 tablespoons; 30g)
1/4 ounce vanilla extract (1 1/2 teaspoons; 7g)
1/2 teaspoon (2g) Diamond Crystal kosher salt; for table salt, use about half as much by volume or the same weight
16 ounces unsalted butter (4 sticks; 455g), softened to about 65°F (18°C)
Fill a wide pot with at least 1 1/2 inches water, with a thick ring of crumpled aluminum foil placed on the bottom to act as a "booster seat" that will prevent the bowl from touching the bottom of the pot. Place over high heat until steaming-hot, then adjust temperature to maintain a gentle simmer. Combine egg yolks, sugar, bourbon or other liquid ingredient, vanilla, and salt in the bowl of a stand mixer.
Place bowl over steaming water, stirring and scraping constantly with a flexible spatula, until egg yolk syrup reaches 155°F (68°C). This should take only about 5 minutes; if the process seems to be moving slowly, simply turn up the heat. Once it's ready, transfer to a stand mixer fitted with a whisk attachment and whip at high speed until mixture is fluffy, stiff, and beginning to ball up around the whisk, about 8 minutes.
With mixer still running, add butter 1 or 2 tablespoons at a time, waiting only a second or two between additions. In the end, the buttercream should be thick, creamy, and soft but not runny, around 72°F (22°C).
Use buttercream right away, or transfer to a large zipper-lock bag, press out the air, and seal. Buttercream can be refrigerated for up to 2 weeks and frozen for up to several months. (The main issue with longer storage in the freezer is odor absorption, not spoilage.) Rewarm to 72°F and re-whip before using.
Troubleshooting: If warmer than 74°F (23°C), the buttercream will be soft and loose; pop it in the fridge for 15 minutes and re-whip to help it thicken and cool. If colder than 68°F (20°C), the buttercream will be firm and dense, making it difficult to spread over cakes and slow to melt on the tongue, creating a greasy mouthfeel. To warm, briefly set over a pan of steaming water, just until you see the edges melting slightly, then re-whip to help it soften and warm. French buttercream can be fixed according to the same rules for Swiss buttercream. For more information, see the troubleshooting guide and video here.
Large pot, flexible spatula, digital thermometer, stand mixer
Though technically optional, using quick-toasted sugar will dramatically tame the sweetness of this buttercream, while also adding subtle depth of flavor. It's a lovely touch for basic vanilla, but not nearly as vital when stronger flavors, like chocolate or spices, come into play.
Make-Ahead and Storage
Use buttercream right away, or transfer to a large zipper-lock bag, press out the air, and seal. Buttercream can be refrigerated for up to 2 weeks and frozen for up to several months. (The main issue with longer storage in the freezer is odor absorption, not spoilage.) Rewarm to 72°F (22°C) and re-whip before using.
|Nutrition Facts (per serving)|
|Amount per serving|
|% Daily Value*|
|Total Fat 13g||16%|
|Saturated Fat 8g||38%|
|Total Carbohydrate 5g||2%|
|Dietary Fiber 0g||0%|
|Total Sugars 5g|
|Vitamin C 0mg||0%|
|*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.|