Heat 2 tbsp olive oil in a heavy-bottomed non-stick pot or large non-stick pan over medium-high heat.
Add garlic, red pepper flakes and rice. Stir to coat rice with oil, and cook, stirring, for 1 minute.
Add chicken stock, saffron and bay leaf. Bring to a boil, cover, then reduce heat to simmer. Cook for 20 minutes.
While the rice is cooking, heat another 2 tbsp oil in another large frying pan, wok or paella pan. Add onion, bell pepper, chicken and chorizo and stir. Cook, stirring periodically, for 7 minutes, or until cooked through.
Add shrimp to the chicken mixture and cook, stirring periodically, for 3 minutes.
Add chicken mixture to cooked rice and mix until combined.