Add 9 tbsps olive oil to heavy hot saucepan.
Add ¾ cups onions, 3 tbsps garlic, and 1½ lbs mushrooms and saute until mushrooms are tender.
Add 9 tbsps flour and cook for about 1 minute.
Deglaze pan with 1½ cups Marsala wine.
Add 4½ cups beef stock and cook until thick and flavors are blended. Add salt and pepper to taste.