Add 1 tbsp of butter and the olive oil to a large pot with a tight fitting lid. Once it's all melted and hot, add the onion, celery and carrot with a pinch of salt. Stir often and cook until everything has had a chance to soften, about 5-7 minutes. Then add the garlic and cook until just fragrant, another minute or two more.

Increase the heat to med-high and stir in the rice and seasonings. Let it cook, stirring often, for about 2 or so minutes to toast up the rice. Then stir in the broth and the chicken and give it all a good stir. Once it starts to come to a boil, cover it with the lid and reduce the heat to low. Cook for a total of 11-14 minutes, until the liquid has all absorbed and the rice is tender... In the last 3 or so minutes of cook time, stir in the peas.

Remove the pot from the heat and immediately stir in the additional 1 tbsp of butter and both of the cheeses until everything is melted and incorporated in. Then serve, topped with a little extra freshly grated parmesan cheese.