Heat the oil in a large, non-stick saucepan over a medium heat. Add the onion and garlic and fry for 2-3 minutes, stirring occasionally, until softened and just beginning to colour.
Add the risotto rice to the pan and stir well for 30-40 seconds, until the oil has coated the grains of rice.
Pour in half of the wine and allow to bubble for 30-40 seconds, then add all of the stock and bring to the boil, stirring well. Reduce the heat and simmer, uncovered, for 8-10 minutes, stirring frequently, until the rice is almost tender and the risotto is creamy in appearance.
Stir in the remaining wine, the chicken and the frozen peas, then continue to cook, stirring constantly, for a further 4-5 minutes, or until the chicken and peas are heated through and the rice is tender with a slight bite.
Remove the pan from the heat, then stir in the butter and cheese. Season with black pepper. Cover the pan with a lid and set aside for 5 minutes before serving.