How I can creation Limited checkboxes in php?

I have a project i put Limited checkboxes by using the javascript The problem is that there you can edit the page using the screening element and skip the limited the Question !! How I can creation Limited checkboxes in php ?

So after that the customer presses a button and the submit is moving to another page is examining a number of selected checkboxes

almost like this

<?php 
if (isset($_POST['grupos'])){
  foreach ($_POST["grupos"] as $pastry) { 
   if ($pastry=="cake") { //make sure the option they chose is part of the options :p 
    echo "<li>Cake</li>"; 
   } 
   if ($pastry=="pie") { 
    echo "<li>Pie</li>"; 
   } 
   if ($pastry=="cupcakes") { 
    echo "<li>Cupcakes</li>"; 
   } 
   if ($pastry=="brownies") { 
    echo "<li>Brownies</li>"; 
   } 
  } 
}
 ?>