Soak bacala for 3 days in cold water, changing water daily. Cut into 1-inch cubes. In a 4 quart sauce pan, heat olive oil until smoking. Add onion and garlic and cook over medium high heat until softened and light golden brown, about 8 to 10 minutes. Add bacala and stir until well mixed with onions. Add wine, tomato sauce, fennel seeds and hot chilies and bring to a boil. Lower heat and simmer 1 hour or until reduced by one third.
Preheat oven to 375 degrees F. Lightly oil 2 10-inch cake pans. Make polenta according to package instructions and, while still hot, pour into cake pans to fill halfway with polenta and allow to cool (about 15 minutes). Divide bacala over polenta among two pans and place in oven to bake 45 minutes. Remove, allow to rest 10 minutes, cut into wedges like a cake and serve with steamed fennel dressed like a salad.
Recipe courtesy of Gourmet Magazine