Bring the stock to a boil then lower the heat and keep it on low heat throughout the recipe. If using saffron threads, reserve 2 tbsp stock in a small bowl and soak the saffron threads (skip if using powdered).
Set a large pan on medium heat and melt half of the butter. Mince the onion and add it to the butter. Sauté for 5 minutes, until soft, reducing the heat if the onion brown too quickly. Add the rice and toast 2 minutes, stirring constantly.
Add enough broth to just cover the rice, stir and simmer until absorbed. Repeat and continue working in batches until all the broth has been added and has absorbed into the rice. Keep on medium-low heat and stir from time to time just to make sure that the rice is not sticking to the bottom of the pan.
After the last addition of broth has been added and has almost completely been absorbed by the rice (the texture is still a bit soupy), remove from the heat. Stir in the saffron, then stir in the rest of the butter and the grated cheese. Serve immediately.
Notes
Never feel tempted to increase the heat to speed up the cooking process. Each addition of stock needs to slowly get absorbed into the rice, in order to cook through each grain. Too high a heat will make the stock evaporate too quickly, not giving the rice enough time to properly absorb the stock. Always keep you risotto simmering on medium-low heat.
The original Milan recipe calls for bone marrow among the ingredients. To compensate for the lack of bone marrow in this recipe I recommend the use of high quality beef stock, possibly home-made. If you have access to bone marrow, you will need about 50g and it will have to go in the pan first together with the butter.
A flavourful stock and the generous amount of cheese that goes into this risotto should mean that no salt needs to be added. Only stir in some at the very end, if the other ingredients did not deliver enough saltiness to your taste.
Please notice that the nutritional information provided is made by an online calculator and is meant to be used as a guideline only. The quantities in this recipe yield 4 portions if serving risotto along with other dishes. If only serving risotto as main, it will yield 3 portions.