Pour the broth into a saucepan and bring to a simmer. Adjust the heat to keep hot.
In a large, heavy saucepan over medium-low heat, melt the butter. Add the onion and saute until beginning to soften, about 5 minutes.
Add the ham and saute until the onion is soft, about 5 minutes longer.
Add the rice and stir until white spots appear in the center of the grains, about 1 minute.
Add a ladleful of the stock and adjust the heat to maintain a simmer. Cook stirring constantly until the liquid is absorbed, about 5 minutes, maybe longer.
Continue adding the liquid, a ladleful at a time and stirring constantly until the rice starts to soften.
Add the peas and continue adding liquid, a ladleful at a time and stirring constantly, unit the rice is just tenter but slightly firm in the center. There will be a creamy appearance with most of the liquid absorbed.
Add the Parmesan cheese. Season with salt and pepper. Stir well to mix.