Boiled is not a word you might think belongs in the same breath as frosting, that whipped and luxurious better half of a cupcake. But for those with long memories or grandmothers with a certain bent towards the traditional, this unlikely phrase will evoke yearning and nostalgic delight.
Boiled, milk, and frosting — here's what it is, and why you really must master it.
What Is Boiled Milk Frosting, and Why Is It Boiled?
Boiled milk frosting was once the most popular frosting for red velvet and devil's food cakes. Unlike other butter-based frostings, boiled milk frosting is thickened by cooking together flour and milk until a thick, pudding-like mixture results, and later butter and sugar are beaten into the cooled milk base.
This frosting goes by several nicknames including roux frosting and ermine frosting, but the most telling might be its nickname of "cloudburst frosting."
Boiled milk frosting is stark white, unlike frosting heavily tinged by butter, and incredibly light in both texture and sweetness. It has a taste akin to traditional buttercream, with subtle cooked milk aftertaste.
While I doubt many of us will be trading our now-traditional cream cheese frosting for boiled milk frosting regularly, it is a handy recipe to keep in your back pocket for a day you run low on butter or need a buttercream without eggs.
Want the best of both worlds? Try a cooked cream cheese icing: Extra-Creamy Cooked Cream Cheese Icing
Making Boiled Milk Frosting
Boiled milk frosting does need more time to make than your average butter and powdered sugar frosting or cream cheese icing. You must cook and cool the flour and milk mixture at least an hour before making the frosting. Similarly to cooking a gravy, whisking the milk and flour together while they cook and thicken will prevent lumps (although don't worry about any lumps, as they will be whipped out later). Off the heat, the flour and milk mixture need time to cool completely and thicken to a custard-like consistency.
Butter and sugar are beaten together until fluffy before the cooked and cooled flour mixture is added, so the longest (and hardest) part of making this frosting is waiting for the milk mixture to cool.
Other Names for Boiled Milk Frosting
Heritage frosting, mock buttercream, ermine, cloudburst frosting, gravy frosting, roux frosting, and also cooked flour frosting, but they are all assembled the same way and result in a frosting somewhere between buttercream frosting and whipped cream.
The Science of Boiled Milk Icing
Why is this icing so creamy and light? Unlike traditional buttercream, which relies on the proteins of egg whites to create a suspension between the sugar and butter, boiled milk frosting utilizes the starches and gluten from the flour to create structure for the butter and sugar. The whole milk also replaces some of the fat from the butter, so that boiled milk frosting requires less of it.
Boiled Milk Frosting
Makes about 3 cups, enough to frost 1 (2-layer) 9-inch cake
(4 sticks) unsalted butter, at room temperature
Whisk the milk and flour together in a small saucepan. Bring to a boil over medium heat, stirring constantly. Boil for 1 minute, then remove from the heat. Transfer the mixture to a small heatproof bowl and press a sheet of plastic wrap directly on the surface to prevent a skin from forming.
Let the milk mixture sit for 15 minutes at room temperature. Refrigerate until cooled completely, about 1 hour. The mixture should thicken to a pudding consistency.
Place the butter and sugar in a stand mixer fitted with the paddle attachment. (Alternatively, use an electric hand mixer and large bowl.) Beat on medium-high speed until lightened and fluffy, about 5 minutes. Stop the mixer and scrape down the sides of the bowl with a rubber spatula.
Add the cooled milk mixture. Return to medium-high speed and beat until well combined, about 3 minutes. With the mixer running, add the vanilla and salt and beat for 1 minute more.
Storage: Boiled milk frosting spreads the easiest on the day it was made, as it continues to thicken as it sits. If you're making the frosting in advance, bring it back to room temperature and beat it lightly before frosting.