First things first; I am not a mint fan, and certainly not a chocolate&mint fan. Noooo, sir. To me, its like chocolate-covered raisins. Bloody waste of chocolate. But, I know people who do like chocolate&mint. I know you’re out there, and you should appreciate this.
I’m not going to give you a recipe today, instead I’ll give you a reference: Baked: New Explorations in baking by Matt Lewis and Renato Poliafito. I’ve referenced them before (see banana espresso muffins) and I’ve read their books many times. If there is one thing I’ve learned, it’s that you DO NOT overmix your brownie batter. It’s like one of the cardinal sins of baking. And its also that everybody can make bakery-worthy treats at home.
So head to the library or bookshop and get baking!