Heya
Firstly, if you want hard copy info, the AWW cookbook has one on the cover (And obviously the recipe for it inside)

Basically, it is made out of 2 cakes, which are baked in 2 different sized pudding steamers or similar. I used porcelain nesting mixing bowls (which were oven safe lol). You could use PYREX glass nesting bowls - they are about $12 and $20 from Matchbox for the size you need.

The 2 cakes are baked and then depending on how (with what) you are icing them, the small one is on the bottom, iced and the second is placed on top, iced and deco'd.
It will depend on the size and weight of the cakes you are using as to whether you want to use cake supports in the bottom to hold the top. I didn't and it worked out fine. You can also use some long bamboo skewers if it is travelling, you just pull them out before you serve it.

Hope that helps