Over medium heat, melt ⅔ of the butter in a large pot. Add the olive oil and onion and sauté for a few minutes until translucent.
Add the rice and fry lightly, stirring constantly and on high heat. Deglaze with a ladle of broth and reduce heat. Simmer until all the liquid has been absorbed.
Then keep adding a little broth and stir constantly. Once the broth is almost completely absorbed, repeat the process. This should take about 20 to 25 minutes in total. The rice should be tender but still somewhat firm to the bite. Then remove the pot from the heat.
Now add the grated parmesan cheese and the remaining butter and mix everything well. Finally, season to taste with salt and pepper.
Pour the risotto into bowls or deep plates and serve hot.Buon appetito!