2Heat a large saucepan over medium heat. Add butter, olive oil and onions and cook for about 5 or 6 minutes.
3Add rice, stir for 2 minutes or until rice is translucent.
4Add wine and stir until it is all absorbed.
5Add the hot stock about 1 cup at a time, stirring frequently until absorbed. Repeat this step until all stock is absorbed and rice is cooked but not mushy. (About 30 minutes.) After about 15 minutes, add lemon zest and juice. Test the rice often towards the end of the time to prevent overcooking.
6When rice is done, turn off heat and add about half of grated cheese. Stir until melted and combined, and serve immediately. Remaining cheese is for sprinkling on top of each serving.