Welcome to the Cake Decorators Q&A

Not too long ago I did a sugarcraft course in my local college and we were told not to put too much buttercream on the outsides of a cake as it reacts with the fondant. I noticed with the cornelli cake Paul put lots of buttercream on before he iced it. Which is the correct way to do it?

Hi Geradine

Butter cream has very high ratio of sugar to butter and when crumb coating a cake it crusts over so there shouldn’t be a problem with discolouration of your icing. I expect that is why you were given this piece of advice.
However, problem can occur with marzipan and royal icing if the marzipan hasn’t been cooked suffciently and allowed to dry. Marzipan is made from crushed almonds which releases oil, so if it isn’t cooked properly it can discolour icing and possibly cause some bacterial growth. Paul uses a lot of butter cream to ensure a complete seal on the cake, he then scrapes it off and lets it completely crust over before applying the fondant. The fondant is thick enough so any oil from the butter would take a long time before making it’s way to the surface if at all.
Everyone has their own interpretations on this but if there was a real issue with BC and fondant, people just
wouldn’t use it. This is only my opinion, the marzipan/icing problem is fact based.