Issue installing BasicTeX with Cask under OS X
TLDR; Add /usr/local/texlive/2015basic/bin/universal-darwin to your PATH.

There is no BasicTeX.app. BasicTex is now installed at /usr/local/texlive/2015basic, wether you use Brew Cask or not (you can also find something files at /Library/Tex, but that's just a bunch of symlinks pointing to the actual installation directory). Just add the above path to your PATH and you should be fine.

Further reference:


BasicTeX installation guide
(non-Brew). aaa
https://tex.stackexchange.com/questions/163849/mavericks-upgrade-screwed-up-my-pdflatex-command-not-found
https://stackoverflow.com/questions/22081991/rmarkdown-pandoc-pdflatex-not-found