Bring the water to a boil according to the boxed directions on the Rice Roni package. Bring the water to a boil. Add the butter or olive oil the mixture. Add the diced onion tot he butter or olive oil and saute until tender. Add the rice and the seasoning packet to the water that is boiling. Turn the stove to low heat and put a lid on the pan. Cook according to the boxed directions. Once the rice is cooked, remove the lid and fluff the rice with a fork. Add in a cup of frozen peas, a tablespoon of fresh or dried parsley and the shredded parmesan cheese. Stir around the pilaf and serve warm.