The broth in the pot should be simmering.
In a large pot slowly simmer the onion and the garlic in the butter, when the onion starts to turn a gold color, remove from the heat and take out the garlic. Add the chopped prosciutto and porcini and mix very well with the onion. Put the pot on heat again, add the rice, and mix very well with the onions, prosciutto and porcini. This is called toasting the rice because the broth has not been added.
After a minute or so start add the broth a ladle full at a time, in order to allow the rice to absorb it. To make risotto creamy you have to mix it a lot adding the broth, as needed.
When risotto is almost done, add the saffron and stir until well mixed. Add a handful of Parmigiano and mix well. Risotto should be soft enough to spread and cover the entire plate when served.
* Risotto with Volpi luganega (a fresh seasonal sausage) is made by substituting Luganega in place of Volpi prosciutto.
Luganega is a very mild lean sausage stuffed in sheep casings. Casings should be removed, sausage broken in small pieces and added to the onion and porcini mushrooms, at the start.
Recipe courtesy of Mario Batali