In a large skillet, heat 1 tablespoon of the olive oil. Add the sausage and cook over high heat, breaking up the meat with a spoon, until browned, about 5 minutes. Add the fennel and cook, stirring occasionally, until softened and lightly browned, about 8 minutes longer. Cover and keep warm.
In a medium saucepan, bring the chicken stock to a simmer; keep warm.
In a large saucepan, heat the remaining 2 tablespoons of olive oil. Add the onion, season with salt and pepper and cook over moderate heat, stirring, until softened, about 5 minutes. Add the rice and cook, for 1 minute stirring constantly to thoroughly coat it with the fat. Crumble the saffron into the wine and add it to the rice. Cook, stirring until the wine is absorbed. Add 1 cup of the warm stock and cook over moderate heat, stirring constantly, until nearly absorbed. Continue adding the stock 1/2 cup at a time, stirring constantly, until it is nearly absorbed between additions. The risotto is done when the rice is al dente and suspended in a thick, creamy sauce, about 20 minutes total. Season the risotto with salt and pepper. Stir in the sausage and fennel along with the cheese, butter and parsley. Serve immediately.