Baking cakes at a lower oven temperature for longer period time will also retain a lot of that moisture. Just be sure to watch it and test it as you go so you don't over bake! Once your cakes come out of the oven, let them cool completely, but don't let them sit out ALL DAY. The edges can get crusty and stale tasting if left out past 12 hours. If you'd like to make this cake in advance, great! Simply wrap the cooled cakes in plastic wrap and leave out on the counter or refrigerate, whatever your preference is.