Okay it took a while but I answered my own question. So if anyone else runs into this problem this is how it goes:
If you started building you game from a template. IntelliSense actually populated the folder “External Dependencies” We have no control over that folder, it can actually be disabled from the UI.
So if there is an external dependency you want to use and it isn’t included in your project simple type:
#include "GameFramework/<any external dependency file name>.h"
now you can call and use that class to your hearts content