Beer Toffee Sauce

I saw an article on Food52.com about making a beer toffee sauce from leftover beer.  Even in the article they said perhaps you never have leftover beer, but that this recipe is worth making anyway.  Open a bottle, use some for the recipe and the rest for the cook :)

How to Turn Leftover Beer into Toffee Sauce

Sounds interesting and stated in the article that beer will work, even a hoppy IPA.  To me, sounds like I might want to try making it with a stout.