Adding Featured Image (post thumbnail) to the 'Content HTML'

I have the [CONTENT] shortcode in my ‘Content HTML’ box but I’d also like to display the featured image at the top of the content.

I’ve tried [image] and [thumbnail] but I suspect this isn’t built in?

Couldn’t find an answer anywhere else, little help? ??

Awesome plugin BTW, throw in Ultimate Taxonomy and it does everything I need!