ajax layout

<?php 
// put this code in app/View/Layouts/ajax.ctp
echo $this->fetch('content');
?>

in your controller's method:

// if the request is via ajax, then render an Element, containing just the little bit of the page you want to update.
if ($this->request->is('ajax')) {
		$this->render('/Elements/my_element');
		return;  // return the form only
}