In a heavy-based saucepan that's large enough to hold the rice with plenty of room left over, cook the onion in 2 tablespoons of the butter over medium heat until it's translucent and fragrant, about 5 minutes.

Stir in the rice and cook it over medium heat for about 3 minutes. Add the wine, 2 cups of broth, and the saffron. Turn the heat to high until the broth comes to a simmer and then adjust the heat to maintain a steady simmer.

Cook until most of the liquid has been absorbed, stirring every minute or two (there's no need to stir constantly). Add another cup of broth and keep cooking, stirring, and adding broth until the rice is al dente but not raw or grainy in the middle.

When the rice is ready, stir in the cheese. Add a little more broth to give the risotto the consistency you like (from fairly tight to almost soupy). Off the heat, stir in the remaining 6 tablespoons butter. Season with salt and pepper and ladle onto heated plates or bowls.

If you try to make risotto ahead completely and then reheat it, it will be overcooked and mushy. Instead, you can cook it until it's about halfway done--the rice should still be rather firm inside--and then spread it out on a baking sheet to stop cooking and cool. Cover the rice and set it aside at room temperature for up to two hours. When you're ready to serve the risotto, return it to the pot and resume adding hot liquid until it's perfectly al dente, a few minutes later.

If you have any leftover risotto, it's delicious made into crunchy Risotto Cakes.