This is a lazy person's braise. Typically, a braise is a tougher cut of meat, like a roast, cooked in a little bit of liquid at at low temperature for a long time. A chicken breast is not a tough cut of meat, and because I knew the point of braising I should have known that the chicken wasn't a good idea. But I trusted Martha Stewart. I thought her braised chicken might just work.
The mushrooms and the polenta, though? Awesome. The polenta made the dish. It's my new favorite food. Top it with the mushrooms and forget the chicken.