Bring the stock, with the saffron to a boil and let it simmer on low heat for 10 minutes.
Melt the butter in a large pan on low heat. Gently fry the onion and add the rice. Fry the mixture 2 to 3 minutes until the grains become translucent. Add the wine, stir and let the mixture cook slowly until the liquid has evaporated. Gradually add the stock; continue stirring while adding 1 cup at a time and wait until the moisture has been absorbed before adding more. Cook for about 20 minutes until the rice begins to look creamy and is al dente.
Turn the heat off and stir the grated cheese into the risotto. Put the lid on the pan and allow the risotto to absorb the flavors for a few minutes.
In a seperate pan heat olive oil and fry the pieces of ham. Remove from from the pan and allow them to drain on a paper towel. Fry the sage leaves in the same pan until crisp.
Divide the risotto into portions on plates and garnish with the crisp ham, sage leaves and few extra fine shavings of cheese.