Layout

index.js

var express = require('express');
var router = express.Router();

/* GET home page. */
router.get('/', function(req, res, next) {
    res.render('index', { title: 'Express' });
});

router.get('/coucou-pug', function(req, res) {
    res.render('layout', { sayHello: 'Hello buddy' });
});
module.exports = router;

layout.pug

html
	head
		title= title
	link(rel='stylesheet', href='/stylesheets/style.css')
	body
		block content
		h1=sayHello
		include includes/header.pug