Twig template engine setup for Wordpress and ACF -

wp_twig.php

<?php
/**
* Setup Twig Templating : http://twig.sensiolabs.org/
* expects a /templates directory to exist in theme directory
* 
* usage with _twig_render wrapper function
* _twig_render($template_path, $data_array);
* 
* 
**/
$loader = new \Twig_Loader_Filesystem(get_stylesheet_directory() . '/templates');
$twig = new \Twig_Environment($loader, array(
    // only use twig cache in production
    'cache' => WP_DEBUG?null:get_stylesheet_directory() . '/templates/twig_cache',
));

/**
 * this function is a wrapper for using the globally created $twig instance
 * 
**/
function _twig_render ($template_path, $vars = []) { global $twig; return $twig->render($template_path, $vars); };