by the way, this is not the exact one, but pretty close to it.
Holy smokes I have no idea for this one. Giving you a bump up so hopefully more people will see this who can help.
actually a relatively simple cake ....tho the detailing will be a killer.
the main body of the hat is nothing more than a 2-tier (4 layers = 8" tall) or even 3-tier (6 layers = 12" tall) stacked tier cake where the tiers are all the same size to start (as opposed to them getting smaller each tier up).
== as drawn below it is 3 tier using the red trim at top to equal layer of cake ==
then a bit of carving to get them to gently slant in to the bottom
then add a gumpaste hat brim
then add gumpaste braids and medallion.
that little red thing (for lack of better term) could easily be fashioned out of a cupcake all iced up in red and the fluffy feathers could be very thin gumpaste that has been cut to be feathery. -- could even add half a miniball pan or a half chocolate shell (think like those Christmas cupcake ornaments) to make it easier to get that big "poof"
fondant could be used in place of gumpaste if you prefer.
as with all stacked tiers -- cakeboard every two layers with proper internal support (SPS or dowels) and stake it like Dracula!
Maybe you could make the feathers out of rice paper? Good Luck!
what is rice paper?