In a pot, heat butter and add onions and garlic and saute. Add the rice into the pot and stir for about 5 minutes, until the rice starts to toast.
Deglaze the pan with some wine and stir. Then add 1/2 cup of broth and stir. As it begins to absorb that liquid, add another 1/2 cup and stir. Do this until the rice is cooked. The Parmesan will thicken the rice a bit so don't let it get dry.