Take the skin off the sausages, and pinch the meat into a non-stick frying pan. Fry meat until crusty and golden, then drain off the oil, and set the meat aside.
Heat the olive oil and half the butter in a pan. Fry the onion gently until softened but not brown. Add the rice, and using a wooden spoon, toss well until the rice is coated in the buttery onions. Pour in red wine and bring to a boil, stirring.
Add a ladle full of the hot stock to the rice. Stir carefully over medium heat until the stock has been absorbed. Continue to add the stock a ladle full at a time. This should take about 20 minutes.
Add the sausage meat, and stir for another 10 minutes until the rice is cooked but not soft.
Turn off the heat and add the Parmesan, remaining butter, and salt and pepper to taste. Stir through. Cover and leave to rest for 3-4 minutes before serving.