Make Ahead and Storage: This cake is even better after a day or so. The moist crumb means it won't dry out easily: you can keep it tightly wrapped in plastic wrap at room temperature for up to 1 week. Why It Works: This cake is really a quick bread; I add more bananas than are commonly used, which keeps the cake extremely moist. Pro Tips: Remember that the toothpick test is tricky when the cake is swirled with something gooey--in this case, Nutella, which will stay melty throughout baking. Make sure you pick an unswirly spot to poke. If you want to get fancy, cut a banana in half lengthwise and lay the halves on top of the batter, cut side up, then bake as directed.