Slice the chicken breasts lengthwise to create four thin pieces of chicken, aka chicken cutlets. If the thickness is uneven, you can flatten the thickest part of the chicken with your hand or a meat mallet. Season the sliced chicken breasts with salt and pepper and dredge in flour.
2 large boneless skinless chicken breasts, ½ teaspoon black pepper, 1 teaspoon kosher salt
Over medium high heat, add half (2 Tbsp) of the olive oil to the pan. Add the chicken and sauté until you get some browning on both sides - about 2 minutes per side. Remove the chicken to a plate, cover and set aside.
4 Tablespoons olive oil
Add the mushrooms, onions and the remaining 2 tablespoon of olive oil. Sprinkle with a pinch of kosher salt and cook for about 4 minutes, until the mushrooms have soaked the liquid up and started to release their juices. Stir frequently.
10-12 ounces cremini mushrooms, ½ medium onion, 4 Tablespoons olive oil
Add the Marsala wine, chicken stock and oregano to the mushrooms and cook on medium high for about 5-6 minutes or until the sauce has reduced and thickened some. It may take longer depending on your stove temperature. Turn the heat to low and whisk in the butter.
1 ½ cup dry marsala wine, ½ cup chicken stock, 1 teaspoon dried oregano, 6 Tablespoons unsalted butter
Add the chicken and their juices back to the sauce, and cook on low for a few minutes. Remove the chicken and sauce to a platter and serve with the parsley.
½ cup finely chopped Italian parsley