Melt the butter in a large, heavy pan and saute the bacon and ham for a few minutes. Add the rice and continue to saute gently for 5 minutes to allow it to absorb some of the fat and flavor. Pour in the wine, let it reduce, then add the stock, a cupful at a time, stirring gently, until the rice is tender. A few minutes before the rice is ready, stir in the Bolognese sauce, if used. Otherwise, remove the pan from the heat when the rice is tender, stir in the remaining butter and the Parmesan cheese, and leave for 2 minutes before serving. Serve the risotto on a hot platter with thin slices of truffle scattered over the top. Serves 6. PASTA 42