There's a little kitchen trick that looks like a magic act: You take something already silky and spoonable, whisk it briefly, and it becomes a cloud with staying power. At first glance, you might expect it to behave exactly like the familiar, feather-light whipped cream that melts away if left too long. The texture is different - a touch denser, a little tangier - and that difference is the clue that something useful (and pleasantly stubborn) is happening under the whisk.