I've recently started looking into making brownies inside silicone molds (in particular, this guy) and I've noticed that it doesn't seem to matter whether I grease, grease & flour, use pam, use parchment paper (with and without grease) or do nothing: the brownies are never guaranteed to come out cleanly. Each method yields some brownies that cleanly separate, with others that lose varying degrees of their bottoms to the pan.  Note: with parchment paper, the problem of a clean release just gets kicked down the road to the stage when I peel the paper off the brownie. Most of the time, the paper pulls a non-trivial amount of crumb off with it.   What's the best way to insure a perfect removal of the brownies from silicon bakeware? 
Freeze the brownies in the mold. They'll release cleanly. 