In a large sauté pan, heat olive oil over medium. Add shallots and cook for 2-3 minutes, or until they start to turn translucent. Add garlic and cook another minute.
Add the mushrooms, giving them lots of room to brown. You don’t want them over crowded or they will steam instead of brown. Cook for 10-15 minutes, stirring often, until they are golden brown.
Add the flour. Stir into the mushrooms and cook for 5 minutes.
Deglaze the pan with the Marsala wine. Slowly add the beef stock to ensure your sauce is thickened.
Add the meatballs and cook until they are heated through.
Serve over polenta, risotto or pasta. Garnish with the fresh chives.