This dish is popular in the Swiss Canton of Ticino. This region shares a border with Italy and Italian is actually the official language! Saffron is grown in the Valais Canton so it should not be a surprise that the Swiss enjoy saffron.
Heat the stock and the saffron threads over low heat so that is barely simmers. Keeping it hot will allow the rice to cook faster and it will cause the saffron to steep, lending that beautiful yellow color to your rice.
Meanwhile, in another saucepan, heat the butter over medium heat and cook the shallots and garlic, stirring to prevent burning, until tender. Stir in the rice so that it is coated with the butter. Stir in the wine and let reduce completely.
Ladle in the stock and saffron, stirring continuously. When the rice is finished, it will be tender, yet have a firmness in the center. The rice should not be dry; add more stock if necessary. It will take about 15 to 17 minutes to cook the rice. Remove from heat and let stand for 1 minute.
Stir in the cold butter and cheeses. Season with salt and pepper.