Custom 500 error page

Another day, another question  .

I have my own custom 404 page set with: 

PHP Code:

$routes->set404Override('App\Controllers\Errors::show404'); 


However, now I want to do the same with the 500 (Whoops we seem to have hit a snag) error.
I don't want to edit the default file, I need to have it pointed to 'App\Controllers\Errors:: show500'.
Can someone point me in the right direction?