https://github.com/dwightwatson/sitemap - very useful utility, works with Laravel 4.*, 5.*.
Install: 
composer require watson/sitemap
Add the service provider to your config/app.php file.
Watson\Sitemap\SitemapServiceProvider::class
Add the alias to the facade, also in config/app.php.
'Sitemap' => Watson\Sitemap\Facades\Sitemap::class
Usage example:
namespace App\Http\Controllers;
use App\Models\Categories;
use App\Models\Essays;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Str;
use Watson\Sitemap\Sitemap;
/**
 * Class SitemapController, generates and shows xml sitemap
 *
 * @package App\Http\Controllers
 */
class SitemapController
{
    public function index() {
        // init sitemap obj
        $sitemap = new Sitemap(
            Cache::store('file'),
            new Request()
        );
        $essayModel = new Essays();
        $categoryModel = new Categories();
        $categoriesArr = $categoryModel->getAllPublishedCategories();
        // add to sitemap all the categories
        foreach ($categoriesArr as $categoryRes) {
            $sitemap->addTag(
                url(
                    "/" . config('custom.urlBases.essaysCategory')
                    . "/" . Str::slug($categoryRes->name, "-") . "-{$categoryRes->id}"
                ),
                $categoryRes->cat_publication_time,
                'daily',
                '0.5'
            );
        }
        $essaysArr = $essayModel->getAllEssays();
        // add to sitemap all the essays
        foreach ($essaysArr as $essay) {
            $sitemap->addTag(
                url(config('custom.urlBases.essayPage') . '/' . $essay->url . '-' . $essay->id),
                $essay->publication_time,
                'daily',
                '0.5'
            );
        }
        return $sitemap->render();
    }
}
Returns content like next:
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
<url>
    <loc>page-url-here</loc>
    <lastmod>2017-02-08T19:52:37+00:00</lastmod>
    <changefreq>daily</changefreq>
    <priority>0.5</priority>
</url>