THC is recieved in the brain by cannabinoids. The mystery of these cannabis receptors in the brain has always been controversal because they are like locks desighned for the THC molecule key.
And THC is grown as a cyrstalic micro-structure on the cannabis plant and the reason for the butter cooking method is that the crystals melt in the hot butter and the surface area of the thc molecules increases.

Hence more surface area of molecule = more THC molecule that will get caught in the Cannabinoid receptors in the brain.

OH GEE DONT I SOUND SMART. YAY BROWNIES!!!!!!!!!!!!!!!!!!!!!!!! WOOT WOOT !! HELL YEAH!!!!!!!!!!!!!!!!!!!!!!! END PROHIBITION AND MAKE HIGH THC HEMP AVAILABLE IN ALL LOCAL GROCERIES STORES ACROSS THE WORLD!!!!