Use a 1cm nozzle to pipe in your butter cream, it will help you keep all the slices even when staking the cakes. Before coating the outside place in a fridge for 30 minutes to set the butter cream, this will make it easier to finish the outside coating.
Place a cake card on the bottom and on top that is the same size as the cake you are working on, make sure they line up.
Roughly pipe butter cream around the edges then using a palette knife spread the cream around then use a flat scraper that is higher then the cake you are working on and scrap around the sides so the scraper is touching the two boards and scrap it nice and clean.
Place the cake in the fridge for 30 minutes then remove the top card and spread butter cream on top. If it starts to go over the edges place back in the fridge and when smooth on top refrigerate for another 30 minutes then take a hot knife to cut off the edges.
This is for a more naked cake finish so you will see some parts of the sponge showing through the butter cream.
To make a smoother finish to the outsides repeat the same as above just make the two boards slightly bigger than the cake.
A great way to finish of this cake is to pipe tempered chocolate over the edges to dribble down and finish with fresh fruit.
Ganache cake:
Use a whipped ganache to cover a cake again in the same way.
Take a strip of acetate that is slightly longer and slightly taller then the cake.
Pipe tempered chocolate along the strip then, using a pallet knife, smooth out the chocolate all over the edges.
With a knife, lift up the chocolate sheet and clean the edges with your fingers then place back down onto the work top.
When the chocolate has semi dried but still flexible wrap it around the cake, and push in the top.
Place back into the fridge for 30 minutes then remove the acetate and finish with fresh berries and icing sugar.