Chicken Livers Banker Style: Fegato di Pollo alla Finanziera

Recipe from Mario Batali

For the risotto:
4 tablespoons sweet butter
1 onion, thinly sliced
1 1/2 cups Arborio rice
5 to 6 cups chicken stock
Salt and freshly ground pepper
3/4 cup freshly grated Parmesan
Chopped parsley leaves, for garnish
3/4 pound chicken livers
2 tablespoons all-purpose flour
3 tablespoons extra-virgin olive oil
1 cup Marsala wine
2 tablespoons chicken stock