In a large ovenproof frying pan, heat the olive oil over medium high heat. Sauté the onion and chorizo until the onion is tender and translucent. Add the chicken, wine, salt and red chilli. Cover and simmer over medium heat for 10 minutes.
Add water to the pan and bring to the boil. Add the butter, then the rice and return to the boil. Quickly transfer to the preheated oven and bake for 10 to 15 minutes, or until rice is tender.