Make broth and put aside to use later.
Put the 20g of butter and the olive oil into a large pot and heat up the mixture.
Then add the onions and garlic if you wish to include them, otherwise you can leave them out. Add the rice to the mixture and cook it until translucent.
This means, cook the rice in the butter and oil until it looks glassy. In Italian you call this "soto voce", the rice is whispering.
When the rice is glassy, add the white wine. Be careful as it will spit, but remember to stir here. Let the wine cook the rice and keep stirring.
Season well and add the saffron. Here I added the chopped up lemons to the rice.
After this keep adding one big spoon of broth to the mixture, stir, and let the broth cook the rice.
Add broth only when the rice looks like it is getting slightly dry in order for the rice to become nice and creamy. Continuously stirring will help the creaminess also.
Finally, add the 50g of butter and the chopped cheese when the rice is al dente. The butter will give the risotto a wonderful flavor and make is soft so don't be too stingy with butter.
If you want a heavier type of risotto you can add whipped cream at this point.