How to Make It
Melt 2 tablespoons of butter in a large skillet over medium heat. Add the mushrooms and cook until they are golden brown on the edges. Remove the mushrooms from the skillet and set them aside.
Mix the salt and the pepper with the flour. Dredge the chicken breast in the flour, shaking off any excess flour.
Add the olive oil to the skillet. When hot, but not smoking add the dredged chicken breasts and cook until it is golden brown on both sides. Remove the cutlets from the skillet and set them aside.
Add the chopped shallots to the skillet and cook them until they are transparent, about 30 seconds.
Add the Marsala and reduce the wine until just a small amount is coating the bottom of the pan, 3 to 4 minutes.
Add the stock and the rosemary and reduce the sauce to half its volume, about 5 minutes.
Whisk the remaining tablespoon of butter into the sauce and add the mushrooms.
Return the chicken cutlets and coat them with the sauce. Continue cooking over low flame until sauce is thickened, 3 to 4 minutes.