To keep that apple cake tasting as fresh as a crisp autumn day, cool it completely before you tuck it away. Slide it into an airtight container or wrap it up snug in plastic wrap. You can keep it at room temperature for a couple of days, or if you're playing the long game, stash it in the fridge. It'll keep there for up to a week, just bring it back to room temp before serving for that just-baked magic.