That's awesome. I love that.
I've never done it, so I can't help you. I have seen some others like it in the gallery though, so hopefully one of those creators will step up with an answer.
Bake and fill each cake. Then cut your wedges. Frost the cakes and wedges in BC and then cover each in fondant and decorate. The construction is pretty much standard just make sure you have enough room for your wedges to sit on. Hope that helps.
I want to add to this that when I made this cake I actually frosted and fondant covered as normal then I used a sharp exacto knife to cut out the wedge...I sliced through the fondant on the top and down the sides of the cake. Then I took a knife and cut the actual cake. I pulled that piece out and then applied fondant to the exposed cake area.
thanks shalderman i think i might try that way as im using sugarpaste