I think it's done the same way as I did mine in my photos. You use modelling chocolate. Roll it out quite thinly, you need them to be about 3 inches high, length doesn't matter. I used ganache on the cake as I doubt buttercream would hold it up. Start at the top and wrap it round, making little Folds to make it wavy and bend some of the tops over. Try not to handle the chocolate too much as it melts easily.
So do I cover the cake first with ganache and let it set then start about half way up and randomly wrap the cake? I tried this with disastrous results and think I'm missing a step.
It would help if you start with a cone shape but without the point. I would start with (as an example) a 10" round, fill and torte it and dowel it, stack an 8" round on top which is filled and torted and dowel that, then place a 6" round on top, filled and torted. Then taper the sides in so that the 10" graduates to the 8" and the 8" graduates to the 6" the slightly taper the sides of the 6" (place a 4" board on top as a guideline). Then ganache the whole of the cake as one. Place a round piece of modelling chocolate to fit the top of the cake. While the ganache is unset apply the strips of modelling chocolate starting at the top of the cake. If the ganache sets up just apply a bit more to adhere the chocolate.
While I agree with the 6,8,10 theory, I don't agree that you need to carve it. If you look closely at the cake you can see where there are distinct layer sizes, so the original was not carved. And it looks like each tier was done separately, not as one.
I disagree, but that's just my opinion. I can't see the breaks in the tiers, I tried to count how many tiers there were but couldn't.
If you look carefully even across from where the flowers are placed, you can see layers. On the layer with the large pink daisy, you can see what looks like the cardboard of the cake, but I believe it is the seam of the white chocolate.
In fact, I think where each flower is placed up along the cake is where each layer is located.