I had an inquiry about this cake. And my question is the little Donuts they are attached to the side of the cake are these cookies and if so what kind of frosting / icing has been used on them? And how are they attached I'm thinking that this is a buttercream? 

could be -- I would use candy clay I think and chocolate -- I would decorate and attach with choco -- and if needed a skewer inside the top of the hole to help hold them on pressed into the cake for added security

I would also have to say that the doughnuts are either modeling chocolate or fondant, and if it’s a buttercream cake, they should just stick right on.  But you can also use melted chocolate, royal icing, or even piping gel.

Actually, I think they might be sugar cookies with royal icing decorations and the top one, as well.  The one plain one appears to have been piped instead of being a cookie.  You could easily achieve the same look by using fondant or modeling chocolate.

yeah if you use cookies you could place them on the side of the cake pan immediately upon removing them from th eoven so they can mold to the side of the cake -- stick the cake pan in a drawer or something so it stay upright on it's side --

These cookies are so small, I doubt it would make much difference whether or not they followed for curve of the side of the cake.