Spiked with rum and reminiscent of mornings at grandma's, this sweet treat all-but-begs for a piping-hot cup of tea. Egg whites are beaten until stiff and gently folded into the batter, making way for a light, airy cake that's baked until crumb-tender in a springform pan. After a final dusting with powdered sugar, it's ready to be sliced into wedges. For an added indulgence, serve alongside marmalade or fruit compote.