Yes, it's young Cora and Rumplestilskin in the season 2 flashback episode The Miller's Daughter, which reveals their backstory. They certainly ought to win some kind of unhealty award: they're both incredibly manipulative people who (de)form (or try to) people into their own image, they pick power over love at key points of their lives, she uses his own tendency to turn phrases in a contract around against him while he comes up with a method to kill her that's positively vampiric on his part, and that's not even all. In between all this, they had a passionate affair. :)