poor-man-twig.wp.php

<?php

$data = array();
/* ... */
		
$tpl_vars = array();
foreach ( $data as $key => $value ) {
	$tpl_vars[ '{{' . $key . '}}' ] = esc_attr( $value );
}

$html = str_replace(
	array_keys( $tpl_vars ),
	array_values( $tpl_vars ),
	$tpl
);