Last night I tried Nancy Silverton's recipe (atop Miette's Hot Milk Cake), and it still looks as perky as can be this afternoon. The secret? Just add 1 part crème fraîche or sour cream for every 4 parts cream, just before it gets to the stage where it can hold soft peaks. Not only does the secret ingredient do wonders for the texture, it adds a lovely, very subtle flavor note, especially if, like me, you leave your cream unsweetened.
Note: I skipped the hand-whisking and did it all in my stand mixer, which is ancient enough as to not even have a whisk attachment. It was still perfect, in my estimation.