We threw it in the freezer for a few minutes, then brushed the chocolate even again on the inside - you need to do this a couple of times before it sets hard enough to not slide back into the bottom of the bowl. Eventually this gives you a nice hardened shell in the bowl.
It's a good idea to make sure the shell comes out of the bowl at this point, and hopefully you'll get a nice, smooth hemisphere of chocolate. Put it carefully back in the bowl once you've checked this, though.
Back to the shortbread - we melted another bag of Buttons and brushed the bottom and sides of the shortbread, then cooled it again to harden the chocolate:
Now it's time for our special ingredient - we emptied all 6 jars of the Fluff into the shell.
This should just be enough to fill the whole shell, but it may not be enough to save it from a tragic fate later on, as we will discover shortly.