Steps

1. Descargue el SmartyView

desde aquí: https://github.com/yukikikuchi/cakephp3-smartyview
Descargar guardar SmartyView como app/src/View/SmartyView.php

AppController.php


class AppController extends Controller {
    public $viewClass = 'App\View\SmartyView';
}

Crear un fichero app/src/Template/Layout/default.tpl

default.tpl


{$this->fetch('content')}