"A Southern favorite, caramel cake boasts a rich toffee-flavored frosting spread over yellow cake layers, but the best part—the caramel frosting that develops a thin, crystalline crust on its exterior—is notoriously troublesome to make. We wanted an easier, even foolproof caramel icing that would stay creamy long enough to frost a two-layer cake. But first, we needed a cake that would be sturdy enough to support the thick frosting. Using the reverse creaming method—beating the butter into the dry ingredients—and switching from cake flour to all-purpose flour gave us a tender, fine-crumbed cake with enough structure to handle the heavy frosting. For a truly easy caramel frosting, we simply simmered the brown sugar and butter before adding cream, and rather than use a candy thermometer we relied on visual cues to know when to add the cream and when to remove the mixture from the heat. To ensure that the icing wouldn’t stiffen before we frosted the cake, we beat a little softened butter into the finished frosting. The fat from the butter kept the frosting soft and spreadable for a few precious extra minutes. After about 30minutes, the crystalline crust formed, while the icing closest to the cake remained silky and smooth...."