bootstrap.php

<?php

namespace Acme\MyApp;

use Rabus\Psr11ServiceProvider\Psr11ServiceProvider;
use Silex\Application;
use Silex\Provider\TwigServiceProvider;

$app = new Application();

$app->register(new TwigServiceProvider());
$app->register(new Psr11ServiceProvider());
$app->register(new ServiceControllerServiceProvider());

$app['my_controller'] = function($app) {
    return new Controller\MyController($app['service_container']);
};
$app->get('/my_route', 'my_controller:myAction');

MyController.php

<?php

namespace Acme\MyApp\Controller;

use Psr\Container\ContainerInterface;

class MyController
{
    private $container;
    
    public function __construct(ContainerInterface $container)
    {
        $this->container = $container;
    }
    
    public function myAction(): string
    {
        // Insert controller logic here.
        
        return $this->container->get('twig')
            ->render('my_template.html.twig', $parameters);
    }
}