How to embed Admin Module Controller in Backend

[Systemcheck82]

Hello,

i have created a admin module with Module generator, added routes and want to use my own Admin Controller which renders a Twig Template.

The Side Link is working but the Controller opens the template without Prestashop Backend around the template.

AdminController without any Logics:

<?php

namespace EasyUpload\Controller;

use PrestaShopBundle\Controller\Admin\FrameworkBundleAdminController;

class DemoController extends FrameworkBundleAdminController
{
    public function demoAction()
    {
        $content = $this->content;
        return $this->render('@Modules/easyupload/views/templates/admin/index.html.twig', [
            'content' => $content
        ]);
    }

    public function getContent()
    {
        /**
         * If values have been submitted in the form, process.
         */
        if (((bool)Tools::isSubmit('submitEasyuploadModule')) == true) {
            $this->postProcess();
        }

        $this->context->smarty->assign('module_dir', $this->_path);

        $output = $this->context->smarty->fetch($this->local_path.'views/templates/admin/configure.tpl');

        return $output;
    }
}

The Result was looking like the result.png attachment. What im expect is like the 2nd picture.

What iam missing to embed my template in the Admin Backend? Any Ideas?