Sprinkle the chicken generously with salt, pepper and herbs de provence

Heat the oil in a large skillet over medium-high heat until very hot but not smoking.

Add 1 tablespoon of the butter and cook the chicken until golden brown on both sides, about 3 minutes per side.

Transfer to a plate and set aside.

Add 1 tablespoon of the remaining butter to the pan and add the mushrooms.

Cook, stirring frequently, until mushrooms are golden brown around the edges and have given off their liquid.

Add the Marsala wine and bring to a boil, scraping to remove any browned bits from the bottom of the pan.

When the wine has reduced by half, add the chicken stock and cook for 3 minutes, or until the sauce has thickened slightly.

Lower the heat to medium and return the chicken to the pan and continue to cook until it is cooked through and the sauce has thickened.

Swirl in the remaining 2 tablespoons of butter, add salt and pepper, to taste.

Garnish with chopped chives and serve immediately.