There is nothing worse than putting time and effort into baking a cake only for something to go wrong when it comes to the most important stage: eating it. According to Chef Todd Mohor, cakes and cupcakes have a tendancy to become too moist when stored under certain conditions or when they are not cooled long enough. This makes adding the icing difficult and gives the baked item a an over-moist taste. Fortunately, there are some easy steps to take that can help decrease the amount of moisture in baked cakes.
Take the cake out of the oven.
Set the cake on top of the stove or counter and let it fully cool before putting it into a container or wrapping it. When a cake is put into storage too soon, the moisture evaporates and sticks to the top of the container or foil. Then, it condenses back down onto the cake creating a mushy texture.
Sprinkle some icing sugar on top of the cake for faster cooling. This will help absorb some of the moisture.
Check for any sticky areas on top of the cake before adding the icing. If there are any, trim them off.
Add the icing once the cake is fulled cooled and the sticky parts have been removed.
After baking cupcakes, remove them from the muffin tin while still keeping the paper attached. Place them on a cooling rack to give them more "breathing room." The moisture is not as enclosed as it would be if the cupcake was in a pan. For another perspective, follow the link in the resources section to see a community discussion on cake moisture problems.