Created more than 100 years ago in the Florida Keys, where the necessary fruit trees were as common as retirees today, key lime pie has been so cheapened and bastardized over the decades that hardly anyone treats the Southern dessert with the respect it deserves. Just Cakes in Bethesda is the exception. Its key lime pie is incredibly refined, its filling silky, light, and tart. The luxurious taste boils down to expensive ingredients and some smart adaptations to the classic recipe. The custard, says pastry chef Steve Scholz, includes about 25 percent fresh juice from Mexican limes and the rest from bottled key lime juice. Instead of topping the custard with meringue, however, Scholz uses fresh, fluffy whipped cream. But that’s about all Scholz will confess to. “I don’t want to give away all our secrets,” he says. Whatever the bakers are doing appears to be working. The key lime pie is a top seller, says Scholz. “It is kind of ironic. We’re Just Cakes, but our key lime pie is really the best.”