Flour Frosting (a.k.a. Ermine Frosting) Recipe

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.