Magento doesn't keep record of which items have been removed, you will have to do that yourself. Start by listening for an event;
app/local/YOURMODULE/etc/config.xml
<config>
...
<frontend>
<events>
<sales_quote_remove_item>
<observers>
<class>YOURMODULE/observer</class>
<method>removeQuoteItem</method>
</observers>
</sales_quote_remove_item>
</events>
</frontend>
...
app/local/YOURMODULE/Model/Observer.php
<?php
class YOU_YOURMODULE_Model_Observer
{
public function removeQuoteItem(Varien_Event_Observer $observer)
{
$product = $observer->getQuoteItem()->getProduct();
// Store `$product->getId()` in a session variable
}
}
?>
Create a session class that extends Mage_Core_Model_Session_Abstract
and use it to store the product IDs you collect in the above observer. You can then refer to that session object (called by Mage::getSingleton()
) to see what products used to be in the cart.