Process all html pages as php in windows hosting modifying web.config file

Question

I inserted PHP code in all my 350 .html pages. It is impossible for me to change all extensions to .php I need to process all .html pages like .php

I found instructions to do it in .htaccess file but my hosting is Windows. I can only modify web.config file, I don't have access to IIS Manager or other resources.

The code I found for .htaccess is:

AddType application/x-httpd-php5 .html .htm

But I need it for web.config file.

Thank you.