In a large skillet heat the oil. When almost smoking, add the onions and garlic over medium-low heat until the onions
have wilted, about 8 minutes. Add the mushrooms
and season with salt and pepper. Raise heat to high and saute until mushrooms are tender and all the liquid has evaporated. Remove pan from heat and pour in Marsala
. Return pan to stove and allow wine
to evaporate, about 3 minutes. Add chicken broth and simmer
for 1/2 hour until the sauce
has reduced by half. Add heavy cream and mix well. Take the pan off the heat and add the fresh herbs
and Parmesan and mix thoroughly.