Adding HTML to the dat format

Hi, I’d like to add some additional markup to the date format, but I’m having trouble. Specifically, I’d like to use:

M d

and add spans around the month and the date.

I’ve tried escaping the pertinent HTML, but this hasn’t worked. Is there a way to do it?

http://ww.wp.xz.cn/extend/plugins/twitter-widget-pro/