In a deep, heavy saucepan, heat 2 tablespoons of the olive oil over medium-high heat. Add the breast meat and cook until browned, about 5 minutes, and remove to a bowl. Add the liver to the pan, and cook until it is just browned, about 4 minutes. Transfer the liver to the bowl with the cooked breast meat. Add the remaining oil to the pan, and cook the onion, celery, carrot, and garlic until lightly browned, about 7 minutes.
Stir in the rosemary, fennel seeds, and red pepper flakes, and cook a couple more minutes. Add the wine, and cook until the liquid is nearly evaporated, about 5 minutes. Meanwhile, crush the tomatoes with your hands, and add them to the pan along with the stock, reserved goose breast and liver, and salt and pepper to taste. Cook over medium heat until thickened, about 20 minutes.
Adjust the seasonings to taste. Spoon the polenta into wide bowls, spoon the ragù on top, and garnish with a healthy sprinkling of cheese.