Risotto alla Valdostana

Chop finely the onion and pour it into a pot with 20 grams of butter and a little bit of oil.
Season it with salt, cover it and cook for a few minutes over low heat.
At this point add the rice and toast it.
Simmer with white wine until reduced over a high flame, then add a ladle of boiling broth and, as it reduces, even more boiling broth. Cook over high heat continuously stirring.
After about 18 minutes, remove from heat, add the remaining butter and crumbled fontina cheese, cover it and let it rest for a few minutes before serving.