I might be making a pull apart cupcake cake for my first official client.  In general, I am not a fan of those cake but after looking at a bunch of pictures it looks like the ones that stand out are the ones that have a perfectly smooth buttercream top - it almost looks like fondant.  What type of buttercream should I be ususing for this cake - a crusting or non-crusting one?  Any other tips?

TIA!

I do tons of these.  I use my regular butter cream.    I take a spray bottle and spray the top with water (after I have the icing on) and smooth with an offset.