Wrap the chicken breasts in cling wrap. Then, pound them with your meat mallet until they measure no more than 1/2 inch. Salt and pepper to both sides. Dredge in flour.
For approximately five minutes, fry the chicken breasts in olive oil. Don't overcook the chicken breasts as they will become very thin and cook quickly. Transfer to a plate and place aside.
In the same pan, heat the chopped shallots for 2 to 3 minutes. Next, add the sliced mushrooms and salt. Saute for 5 minutes. Finally, add 1 tbsp flour. Stir and cook for another minute. Then add the chicken stock. Reduce heat to medium and bring to boil. Once the sauce has boiled, reduce heat to a simmer. Let the sauce simmer for a while to let the sauce thicken.
Sprinkle with chopped parsley and serve with a side dish.