//MyHelpers.cshtml:
//Recursive function for rendering child nodes for the specified node

@helper CreateNavigation(int parentId, int depthNavigation, int currentPageId)
{
   @MyHelpers.Navigation(parentId, depthNavigation, currentPageId);
}

@helper Navigation(int parentId, int depthNavigation, int currentPageId)
{

   if ()
   {
       if ()
       {
         <ul style="">
            @foreach ()
            {
               if ()
                {
                   <li class="">
                      @Navigation(child.Id, depthNavigation, currentPageId)
                   </li>
                }
             }
         </ul>
      }
   }
}

//I call the method in _Menu.cshtml:
 @MyHelpers.CreateNavigation(rootNode.Id, 2,currentPageId);