For the risotto milanese, sauté the finely diced onion in half the butter until soft, add the rice and stir well. After a few minutes, deglaze with the wine and stir at a good temperature until the liquid has almost completely evaporated.
While continuing to stir, gradually add boiling beef broth; the rice should always be just covered with liquid. If it becomes drier, add more liquid.
After the cooking time, the rice should be soft but still have a firm core inside. The consistency of the risotto should be mushy. Finally, remove the saucepan from the stove and fold in the remaining butter and grated cheese.
Garnish the risotto milanese with fresh prosciutto and serve hot.