Finely chop the onion. In a pan put the chopped onion and half of butter and cook it gently for few minutes.

Then add the rice and roast for 1 or 2 minutes, add the wine and leave it to evaporate.

Add the stock, one ladle at a time, and cook the rice for about 10 minutes, stirring almost continually.

Add the saffron at this point and finish cook the rice adding more stock as necessary. Cooking time depends on the quality of rice you are using; usually it is 18 minutes, start after you roast it.

At the end add the remaining butter, a few spoons of grana, and stir thoroughly.