There are buttercreams made with butter and powdered sugar, and there are buttercreams made with butter and egg whites. But for the most silky, decadent buttercream of all, try this French buttercream made with egg yolks.
Back when I was a pastry chef, I made buttercream by the gallon in a huge industrial mixer that stood in the corner and made the floor shake with its vigorous beating. We used this buttercream on all our layer cakes, from simple devil’s food to the most elaborate wedding cake. It’s based on a recipe from the first volume of Julia Child’s “Mastering the Art of French Cooking” with a few minor adjustments.
Buttercreams made with egg yolks take the richness factor up a few notches, turning it into a silky and sexy but not-too-sweet way to frost your cakes. You can pipe decorations with this buttercream, but it is a little looser than egg white or powdered sugar variations, so expect softer, more billowy results.
I recommend using very high quality eggs, which often have deep orange yolks and will make a beautiful, soft yellow buttercream. The hot sugar syrup (238 degrees) added during mixing cooks the egg yolks a bit, but not enough to pasteurize them. If you’re cautious about raw eggs or have a health issue, you may not want to use this recipe.
A stand mixer comes in handy here, especially when pouring the hot sugar syrup into the egg yolks, but a hand mixer will do in a pinch. I do not recommend making this without an electric mixer unless you have very well-developed arm muscles!
Temperature is key with this recipe. The egg-sugar mixture should be absolutely cool before you begin adding the butter, and the butter should be just slightly softened, just a little cooler than room temperature. You can test this by pressing on a piece with your finger. It should give enough for you to press into it, but it should take some effort. Under no circumstances should you melt the butter or expose it to anything warmer than room temperature. Melting the butter irrevocably changes its texture, separating solids from fat.
The finished buttercream can be stored for a few days in the refrigerator, but allow time for it to come to room temperature before you frost cakes or cupcakes. Do not heat it up, as this causes the butter to melt and the buttercream to break.
One last thing – don’t toss out the egg whites! If you don’t have an immediate use for them, cover and refrigerate for a few days or freeze them for later use.
UNWRAP the butter and cut it into large pieces, about 8 per stick. Leave on counter. If your kitchen is particularly cool, you may want to do this about 15 minutes ahead of time. (If your butter is frozen, thaw in the refrigerator overnight before using.)
COMBINE the sugar and water in the small saucepan and place on the stove over medium heat.
ADD the yolks and pinch of salt to the bowl of a stand mixer fitted with the whisk attachment. Whisk on high speed until pale and thick.
WHEN the syrup reaches the soft-ball stage (238 degrees on a candy thermometer), remove from heat. With the mixer on low speed, slowly add the syrup to the yolks to avoid splattering the syrup on the beaters. Stop pouring every 10 seconds or so and increase the speed to high, then switch it to low and drizzle in more syrup. Do this until all the syrup is incorporated.
AFTER all the syrup has been incorporated, beat on high speed until the mixture has cooled to room temperature. This can take about 10 minutes. When the mixture and the bowl no longer feel warm, switch to the paddle attachment and start adding the butter one cube at a time, mixing well between each addition.
ADD the vanilla (or other flavoring) and beat until the buttercream is smooth and slightly stiff.
NOTES: You can add other flavorings besides vanilla, such as 2 tablespoons of brandy or strong coffee, peppermint extract, etc. For chocolate buttercream, melt 1 cup of semisweet chocolate chips in 2 tablespoons of hot coffee or brandy. Stir to combine and cool to room temperature. Add to the buttercream and beat well. YIELD: About 2 cups, enough to frost a two-layer 8-inch cake.
Dana Velden is a writer for TheKitchn.com, a website for food and home cooking.