There can be a problem with fillings spilling out the sides of the cake. There are ways to stop this from happening when your cake decorating involves a filled middle.
1. Bake your cake the day before you are planning to fill it. This will make the cake firmer and will give it time to settle. A freshly baked cake will be unstable and will not hold fillings as well as when they are settled.
2. You can also use icing to make a dam to stop the filling from spilling out. Once the dam has been made, you can frost the whole cake with a crumb coating. The cake should be set in the refrigerator for 2 to 3 hours, or overnight, this will firm up the icing and will keep the filling from oozing out the sides. The dams made of icing will firm up and keep the filling in.
If you are a busy person and don't have time to bake and decorate a cake all at once, you can bake the cake and freeze it until you need to decorate it. A cake can be kept in the freezer a couple of weeks before it needs to be used. You must prepare the cake for freezing by wrapping three layers of strong cling wrap around the cake, followed by one layer of aluminum foil just prior to freezing. If you do not follow this procedure, your cake will dry out and crumble. You will also need to make sure the cake is completely thawed before attempting to ice it.
You will need to allow the cake to defrost slowly, at room temperature, for one or two days until it has defrosted. Icing a cake before it has thawed will make the icing sweat and become mushy, this will ruin your cake decorating, and all your hard work will be for nothing.