To prepare the chicken, season the flour with salt and pepper. Slice the chicken breasts to 1/4-inch-thick medallions. Coat with the flour and tap off any excess.
Next, in a saucepan over medium heat, add enough oil to coat the bottom of the pan and allow to warm. After warming, add the chicken and cook until browned, 2 to 3 minutes. Flip and repeat the process. After cooking all the chicken, hold warm covered on a plate. Add the marsala to the pan over medium-high heat. This will deglaze the pan. After deglazing, reduce the wine by three-fourths volume so 2 ounces remain. Then add the mushrooms. Stir the mushrooms, scraping the sides, then finish with the veal stock. Allow the stock to warm and thicken for 4 to 5 minutes, and then remove from the heat. Stir in the butter and finish by spooning over the cooked chicken. Garnish with fresh herbs or cheese if desired.
Robert Irvine's eat, All rights reserved 2011