In a 4-quart saucepan, heat olive oil over a medium heat. Add onions and garlic and sweat for 3 minutes until vegetables are translucent and aromatic. Add rice and lightly toast in oil for 2 minutes stirring frequently. Add liquid 1/3rd at a time stirring until each additional 1/3rd is absorbed. Once all liquid is absorbed, remove from heat and stir in Parmesan, parsley, and butter.
Divide into 6 servings and top with shaved truffles.