Guys,

How would you do the plague/cake topper/monogram on the top of the cake. its not to be chocolate, to be white....

any thoughts....

I'd use white chocolate or make it out of pastiage.

It seems like it would be pretty easy to make the rectangle shape out of thickly rolled gumpaste. I would either use gumpaste for the monogram, or just pipe it on.

i thought it woulde be easy also, but looking at it closely, it looks as if it is attached to a base of some kind...

Are you sure its edible?

I'd use pastillage or chocolate. Any way you can think of to make a mold for it? That would make it easy to make out of chocolate.
There is definitely a base on it. That's going to be the tough part, and why I think they used a mold. Maybe get some silicone, find a blank plaque with base at a craft store, ice initials in royal and leave dry, then make a mold of the whole thing?

I'd make two slabs - one for the upright, one for the base. Let them dry and then attach the two together, then let dry again.

You could do the lettering with a clay-gun if you have one, or just by piping it on. I'd do this before attaching the two slabs together.