Why It Works
- A combination of vanilla beans and extract give this buttercream a deep vanilla flavor.
- A thick pudding base provides the buttercream with sweetness, structure, and volume.
- Temperature guidelines help avoid common textural problems.
This old-school frosting combines whipped butter with a thick vanilla custard, which gives it flavor, sweetness, and stability all at the same time. While it tastes like the creamiest vanilla soft serve, it's a buttercream with more than enough structure to support even the tallest layer cake. Its light simplicity is a natural match for dense and nutty European tortes, while that same fluffiness makes it equally well-suited to even a down-home Texas sheet cake.
- 12 ounces milk, any percentage will do (about 1 1/2 cups; 340g)
- 1 vanilla bean, split lengthwise, or other aromatics such as fresh herbs or whole spices
- 8 ounces sugar (about 1 cup plus 2 tablespoons; 225g)
- 1 1/2 ounces cornstarch (about 1/3 cup, spooned; 45g)
- 3 large eggs, straight from the fridge (about 5 1/4 ounces; 150g)
- 1/2 ounce vanilla extract (about 1 tablespoon; 15g)
- 20 ounces unsalted butter, softened to about 68°F (5 sticks; 565g)
To flavor the milk: In a 3-quart stainless steel saucier, combine the milk and split vanilla bean (or other flavorings) over medium heat. When the milk is steaming hot, remove from heat, cover, and steep at least one hour. Proceed as directed below, or refrigerate up to 24 hours to extract a deeper flavor before proceeding.
To make the custard: Whisk the sugar and cornstarch together in a medium bowl, followed by the eggs.
Return milk to a simmer and discard vanilla bean after scraping out the flavorful seeds and pulp inside (or remove other flavoring elements, and scrape them as best you can, if possible). Ladle 1/2 cup hot milk into the eggs and whisk to combine. Repeat with two more 1/2-cup additions, then pour the warmed eggs into the pot. Cook over medium heat, whisking constantly, until the custard turns thick and lumpy, about 3 minutes (the timing can vary depending on the specifics of your stove and cooking vessel, so adjust the heat accordingly if it seems to move too slow). As soon as the custard begins to bubble, set a timer and continue cooking and whisking for exactly 2 minutes longer. This helps neutralize a starch-dissolving protein found in egg yolks.
Off heat, stir in vanilla extract, then pour custard into a large baking dish to speed the cooling process. Press a sheet of plastic against the surface and refrigerate until thick and cool, about 1 hour, or to roughly 68°F. Alternatively, refrigerate up to 1 week, then stand at room temperature until warmed to roughly 68°F.
For the Buttercream: In the bowl of a stand mixer fitted with a paddle attachment, beat the softened butter on medium speed until fluffy and light, about 5 minutes. Meanwhile, stir the thick pudding in its dish to create a thick, dough-like mass. Add pudding a few tablespoons at a time, one right after the other, then scrape the bowl and beater with a flexible spatula, and beat a few seconds longer.
Switch to the whisk attachment and whip on medium speed until the buttercream is airy, soft, and light enough to weigh approximately 6 ounces per cup. A heavier weight per cup indicates the frosting is too cool, and/or under-whipped, and will result in a dense, greasy frosting that may seem too sweet. To adjust the frosting's consistency, warm over a water bath until the edges have just begun to melt, then re-whip. For more detailed instructions, consult our buttercream troubleshooting guide.
Use buttercream immediately, 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 approximately 72°F and re-whip before using.
Stand mixer, flexible spatula, whisk, 3-quart stainless steel saucier