Ermine frosting is an old-school buttercream made with just four ingredients: butter, sugar, flour, and milk (okay, six ingredients, if you count salt and vanilla). It feels as light and silky as whipped cream, but it's far more stable. It's also an easy, eggless alternative to European buttercreams, like Swiss and Italian, but it's substantially less sweet than American buttercream.
Why It Works
- Cooking the flour alone in milk allows it to fully cook, activating its thickening power and eliminating any raw or starchy flavor.
- Adding sugar to the finished flour paste ensures it melts completely but doesn't interfere with the cooking process.
- A paddle attachment works best to ensure the frosting is smooth, while the whisk attachment helps it fully aerate.
- Yield:Makes about 2 heaping cups (14 ounces)
- Active time: 15 minutes
- Total time:About 1 1/2 hours
- 1 ounce all-purpose flour (about 3 tablespoons plus 2 teaspoons; 28g)
- 6 ounces milk, any percentage will do (about 3/4 cup; 170g)
- 3 1/4 ounces (96g) plain or toasted sugar (see note)
- Heaping 1/4 teaspoon (1.5g) Diamond Crystal kosher salt, plus more to taste; for table salt, use about half as much by volume or the same weight
- 6 ounces (160g) unsalted butter, softened to about 65°F (18°C)
- 1/4 ounce vanilla extract (1 1/2 teaspoons; 7g), plus more to taste
In a 10-inch skillet or 3-quart saucier, whisk together flour and milk. Place over medium heat, whisking constantly, and cook until thick and pudding-like, about 2 minutes. Off heat, add sugar and salt. Whisk until sugar has dissolved and the "pudding" is homogeneous but thin. Scrape mixture into a wide, shallow dish, such as a pie plate, and cool to approximately 70°F (21°C).
Place butter in the bowl of a stand mixer fitted with a paddle attachment. Mix on low until the butter looks smooth, then increase speed to medium and beat until soft and light, about 5 minutes. Begin adding the cooled pudding, a few tablespoons at a time. Once it's fully incorporated, pause to scrape bowl and beater with a flexible spatula, then resume beating until perfectly smooth.
Switch to the whisk attachment and add vanilla. Whip on low to combine, then increase speed to medium-high and continue whipping until silky-smooth and soft, with a light, melt-in-your-mouth consistency, about 3 minutes more, or to a working temperature of approximately 75°F (24°C). Season to taste with additional salt and/or vanilla as needed. Use immediately, or consult the troubleshooting guide below to address any textural inconsistencies.
Troubleshooting: If the frosting feels dense, stiff, greasy, or curdled, it is likely too cold; to warm, briefly set over a pan of steaming water, just until you see the edges melting slightly, then re-whip. If the frosting feels soft and loose, it is likely too warm. Pop it in the fridge for 15 minutes to cool, then re-whip.