public class HeaderController : Controller
    {
        private IMenuService _menuService;

        public HeaderController(IMenuService menuService)
        {
            this._menuService = menuService;
        }

        //
        // GET: /Header/
        public ActionResult Index()
        {

            return View();
        }


        public ActionResult GetMenu()
        {

            MenuItem menu = this._menuService.GetMenu();
            return View("Menu", menu);

        }

    }

public class MenuService : IMenuService
{
    private IMenuRespository _menuRepository;

    public MenuService(IMenuRespository menuRepository)
    {
        this._menuRepository = menuRepository;
    }

    public MenuItem GetMenu()
    {
        return this._menuRepository.GetMenu();
    }
}

public class MenuRepository : IMenuRespository
    {
        public MenuItem GetMenu()
        {
            //return the menu items
        }
    }

public interface IMenuService
    {
        MenuItem GetMenu();
    }

public interface IMenuRespository
    {
        MenuItem GetMenu();
    }

MenuItem menu = new MenuService(new MenuRepository());