Add the stock to a medium pan over low heat and gently simmer.
Bring a large saute pan at medium heat, once hot, add the olive oil, onion and cook for 2-3 minutes. Add the garlic, stir and add the arborio rice. Cook, stirring frequently for 1 minute.
Pour the white wine and stir, allowing the alcohol to evaporates, about 1 minute.
Pour 1 cup of the stock and stir well with a wooden spoon. Simmer on medium-low heat, uncovered for 5-6 minutes until all liquids were absorbed by the rice.
Place the pan with stock on the stove next to the risotto saute pan with a ladle.
Continue to cook the rice by adding a ladle of stock each time the risotto dries out. Stir frequently with a wooden spoon and repeat this process until most of the stock is incorporated into the risotto, about 20 minutes until the rice is al dente. Save about 1/2 cup of the stock.
Check the consistency of the risotto, the rice should be soft on the outside and gently crunchy in the middle. At this point, add the chicken, peas and another ladle of stock, give a gentle stir to incorporate the new ingredients. Continue to cook to heat the peas and chicken. Remove from the heat.
Add the cold butter and stir gently but frequently to melt and finish with the grated cheese.
Season with black pepper and serve immediately.