Preparation

• In a small bowl, whisk the sugar and flour, breaking up any lumps of flour.
• In a 4-quart heavy-duty saucepan, bring the milk and cream to a boil over medium-high heat. Reduce to medium low and whisk in the flour and sugar a little at a time until incorporated. Increase the heat to medium high, bring the mixture to a boil, and cook, whisking frequently, until thickened to a pudding-like consistency, 10 to 11 minutes.
• Strain through a medium-mesh sieve into the bowl of a stand mixer fitted with the paddle attachment. Beat on high speed until cool, 7 to 8 minutes. Reduce to low and add the vanilla.
• Add the butter a few pieces at a time, increasing the speed to medium after most of the butter is added. Stop the mixer after all of the butter is incorporated; the frosting will look chunky. Let it sit at room temperature for at least 2 hours and up to overnight.
• With the whisk attachment, whip the frosting on medium-high speed to emulsify and incorporate air; this will take up to 20 minutes. The frosting should become more pale and voluminous. If too soft, place the bowl in the refrigerator to chill slightly, then beat again. If too firm, set the bowl over a pot of simmering water and beat until spreadable. If at any point during frosting it looks broken, simply rewhip it. You can’t overbeat it.
• Use on our Very Vanilla Cake or on your favorite 8- or 9-inch triple-layer cake.