Storing instructions: store leftover cake in an airtight container or covered with plastic wrap for up to 3 days in the refrigerator. Before eating, I recommend letting the cake come to room temperature for at least 30 minutes. Freezer: you can freeze banana cake with the caramel topping for up to 2 months. Wrap tightly with plastic wrap before storing. To thaw, pull it out to room temperature for about 1 hour while you make the caramel topping.