Heat the olive oil in a large saucepan over medium heat. Add the onion and garlic and cook until softened, about 5 minutes.
Add the rice and stir to coat with the oil. Cook for 1 minute.
Add the white wine and stir until it is absorbed.
Add 1 cup of the hot broth to the pan and stir until it is absorbed. Continue adding 1 cup of broth at a time, stirring until it is absorbed before adding more.
When all of the broth has been added and absorbed, remove from heat. Stir in lemon juice, butter and Parmesan cheese.