In a large paella pan or wide, shallow skillet, heat the olive oil over medium heat.

Add the chicken pieces and cook for about 5 minutes, or until they are lightly browned on all sides. Remove the chicken from the pan and set aside.

Add the sliced chorizo to the pan and cook for about 3-4 minutes, or until it starts to release its oils. Remove the chorizo from the pan and set aside with the chicken.

In the same pan, add the chopped onion, garlic, red bell pepper, and yellow bell pepper. Cook for about 5-7 minutes, or until the vegetables are softened.

Stir in the rice, smoked paprika, crushed saffron threads, and cayenne pepper (if using). Cook for about 2-3 minutes, stirring constantly, until the rice is well-coated with the spices and slightly toasted.

Pour in the warmed chicken broth and crushed tomatoes. Season with salt and freshly ground black pepper to taste. Gently mix everything together, ensuring that the rice is evenly distributed in the pan.

Bring the mixture to a boil, then reduce the heat to low and let it simmer, uncovered, for about 15-20 minutes, or until the rice is almost cooked and has absorbed most of the liquid. Do not stir the rice during this time, as this will cause it to become sticky.

Arrange the browned chicken and chorizo on top of the rice, followed by the shrimp, mussels or clams, and peas. Press the seafood gently into the rice.

Cover the pan with a lid or foil, and continue to cook for about 10-15 minutes, or until the shrimp are pink and cooked through, the mussels or clams have opened, and the rice is tender.

Remove the pan from the heat and let it rest, covered, for about 5 minutes.

To serve, discard any unopened mussels or clams, and sprinkle the paella with chopped fresh parsley.

Serve the paella directly from the pan, along with lemon wedges for squeezing over the top. Enjoy!