So the nuts and the sugar mixture are mixed together and then placed into the bottom of a pie tin, so that later on when the pie is made to be upside down the second time (the first time being when it's made upside down), the top becomes the bottom and the bottom ipso-fatso becomes the top. And so this is an amazingly clever way to put stuff on the top of a pie without actually putting it on the top.
Take THAT, pie man!
Note that even though the pie shells we bought had pie tins underneath them (the better for making pie), we hate the environment so much that we actually went out and bought an extra pie tin, then took the pie crust out of the tin it came in, threw it away, and THEN used the extra pie tin for this purpose. Man, we're bastards.*
* Most of this is a blatant lie just for the sake of lying.