ZZCX_yii/backend/modules/zzcs/controllers/DefaultController.php

<?php

namespace backend\modules\zzcs\controllers;

use yii\web\Controller;

/**
 * Default controller for the `zzcs` module
 */
class DefaultController extends Controller
{
    /**
     * Renders the index view for the module
     * @return string
     */
    public $layout = 'zzcs';

    public function actionIndex()
    {

        return $this->render('index');
    }
}