It works basically as any other template. Here's an example how i use/solved it.
# controller - genrate content for e-mail
$content = $this->view->getRender('emails', 'reset-password', ['token' => $uuid, 'url' => $this->config->application->domainUri]);
# views/emails
<html>
<body>
<p>We received a request to reset your password.</p>
<p>Use the following link to reset your password: <a href="{{ url }}{{ url("auth/reset/" ~ token) }}" >{{ url }}{{ url("auth/reset/" ~ token) }}</a></p>
</body>
</html>