How to Make It
Preheat the oven to 350°. Season the chicken with salt and pepper. Heat the oil in a large ovenproof skillet. Add the drumsticks and cook over moderately high heat until browned all over, about 8 minutes. Transfer the chicken to a plate.
Add the onion and bell pepper to the skillet and cook over moderately low heat until softened, about 5 minutes. Add the garlic, saffron and cayenne and cook, stirring, until fragrant, about 2 minutes. Add the rice and stir until lightly toasted, about 3 minutes. Add the chorizo and tomatoes and cook, stirring, for 2 minutes. Stir in the chicken stock and simmer over moderately high heat until the liquid has slightly reduced, about 4 minutes. Stir in 1 teaspoon salt and season with pepper.
Nestle the chicken in the rice and cover tightly with foil. Bake the paella in the center of the oven for 30 minutes. Turn the oven up to 450°. Scatter the peas over the paella and arrange the clams, hinge down, on top. Cover with foil and bake for about 8 minutes, or until the clams are open and the chicken is cooked through. Loosen the foil and let the paella stand for a few minutes. Garnish with the scallions and serve.