Makes about 3 cups/685 ml frosting
IF YOU’RE ONE OF THOSE PEOPLE WHO CLAIMS TO “HATE FROSTING” BECAUSE it’s too sweet, I urge you to give this old-fashioned formula a try. It all starts with a roux of sorts that gives the frosting the kind of body you’d normally get from heaps of confectioners’ sugar. With a good whipping, it becomes almost the consistency of whipped cream—remarkably light and so fluffy you’ll want to dive right in with a spoon.
This batch is the perfect amount for the Swedish Flop (here) and a 9 × 13-inch/23 × 33 cm sheet cake. It will modestly frost a two-layer 8-inch/20 cm cake, so if you like a loftier frosted look for layer cakes, make 1½ batches.
¼ cup/32 g unbleached all-purpose flour
1 cup/225 g whole milk
1 cup/200 g granulated sugar
¼ teaspoon fine sea salt
1 cup/225 g unsalted butter, at room temperature
1 teaspoon pure vanilla extract
¼ teaspoon pure almond extract
In a 2- to 2½-quart/1.9 to 2.4 L saucepan over medium heat, whisk together the flour, milk, sugar, and salt. Continue to whisk until the mixture comes to a full boil. Cook for 1 minute, whisking constantly, until the mixture resembles pudding. Remove the pan from the heat. Let cool completely at room temperature, or to speed up cooling, scrape the mixture into a clean bowl, cover the surface with plastic wrap, and chill in the refrigerator.
In the bowl of an electric mixer fitted with the whisk attachment, whip the butter with the vanilla and almond extract on high speed for 2 minutes. Scrape down the bowl and add the cooled flour mixture. Beat until the frosting becomes very fluffy, almost mousselike in texture, and noticeably lighter in color, about 5 minutes. Use immediately.