Sweat the first 5 ingredients in a little fat. Add the risoni and a ladle of the broth and stir well. Simmer a little and stir in two more ladles of the stock. Mix in the saffron. When the liquid is almost completely absorbed, add the stock again. Proceed in this way until the risoni are cooked, but still very firm to the bite. Stir more often.
Remove from heat, stir in the parmesan and let the Risoni risotto stand for about 5 minutes, covered.
Sprinkle some parmesan on top and serve very warm.