In a medium saucepan, create a Parmesan broth by adding water and Parmesan rinds. Bring broth to a simmer, cover saucepan, and keep hot over low heat.
In a large, heavy bottomed saucepan, melt 2 tablespoons of the butter over medium heat. Add the onion and sauté until tender, but not brown, for 3 minutes. Add the rice and stir to coat with butter. Add wine and simmer until the wine has almost completely evaporated for 3 minutes.
Add 1/2 cup of the simmering Parmesan broth and stir until almost completely absorbed for approximately 2 minutes. Continue cooking the rice adding a 1/2 cup of broth at a time. Stir constantly and allow each addition of broth to absorb before adding the next until the rice is tender but still firm to the bite and the mixture is creamy, for 20 minutes.
Remove the large saucepan from heat. Stir in the Parmesan cheese, the remaining tablespoon of butter, and salt and pepper. Transfer the risotto to a serving bowl and serve immediately. Garnish with shaved Parmesan (optional).