Heat the oil in a pan or skillet and brown the chicken pieces on medium-high heat. This should take around 5 minutes.
Reduce heat to medium, add the onion and saute until golden (about 5 minutes).
Add the garlic and chorizo, and cook for 5 minutes until the chorizo releases the rich red oil. Set all ingredients aside for use later.
Preheat oven to 390°F / 200°C
Add the grated tomatoes, herbs and spices, and white wine (optional) to the pan along with 2 ladles worth of chicken stock and simmer on medium heat for 5 minutes.
Add the chili flakes and a full sprig of rosemary and simmer for 2-3 minutes more or until fragrant.
Remove the sprig of rosemary. Add the rice and mix into the sauce along with another 1-2 ladles worth of chicken stock.
Add the browned chicken, onions, and chorizo back to the pan and bring to a boil for 5 minutes. Season to taste.
Give everything a good stir and ensure all the rice is covered with stock. Add pan if ovenproof or transfer to a casserole dish to the oven and bake for 20-30 minutes at 390°F / 200°C.
