Add the chicken stock to a pot, season well with salt and pepper and heat until hot. Keep warm.
Meanwhile, heat a large round saucepan over medium heat and add the oil. When hot, add the sausage and cook, without stirring, until brown on both sides, 2 to 3 minutes per side. Break up the meat with a wooden spoon.
Add the onions and sweat for 1 minute. Add the rice, toss to combine, and lightly toast in the fat. Add the wine and cook, stirring, until the wine is absorbed.
Add 1 cup of the stock and cook, stirring, until the stock is absorbed. Continue to add the stock 1 cup at a time and cook, stirring after each addition until absorbed, until the rice is al dente, about 20 minutes. Add the peas. Remove from the heat and stir in the Parmesan, parsley and butter.
For more ingredient substitution ideas, see the article below.