If you're tempted to tweak and doctor Alice's deceptively simple recipe, don't. She knows what she's doing, and her brownies are perfect as-is -- even if, like me, you don't usually care for walnuts in your brownies. The nuttiness of the brown butter is enhanced by the walnuts, which themselves make for a satisfyingly toothsome bite.
But if you absolutely insist on making another batch with globs of Nutella swirled on top, I won't stop you. Either way, they make a perfect Valentine's Day treat.