Preheat the oven to 180°C (350°F/Gas Mark 4).
Add 1 tablespoon of rapeseed oil to a large casserole dish with a lid. Add half the butter and place on the hob to heat. Season the chicken, add to the dish, skin side down, and cook for 2-3 minutes until lightly browned. Turnover and cook for another minute or so until sealed. Transfer to a plate and set aside.
Add another tablespoon of oil together with the remaining butter, then tip in the onion and garlic. Sauté for 2-3 minutes until softened but not browned. Add the chorizo, rice and smoked paprika and cook for another 2 minutes, stirring regularly until the chorizo has begun to release its oil and all the rice grains are well coated.
Pour the wine into the dish, stirring to combine, then add the stock. Arrange the chicken on top, pushing down into the rice. Cover with the lid, place in the oven and bake for 20-25 minutes until all the liquid has been absorbed and the chicken and rice are cooked through and tender. Add in the frozen peas, stir through and cook for a further 5-10 minutes.
Remove from the oven and scatter over the parsley and place directly on the table to serve.