In a very wide pan or paella pan, preheated over medium high heat, add 2 tablespoons extra-virgin olive oil, 2 turns of the pan, crushed garlic, red pepper flakes, add rice and saute 2 or 3 minutes. Add saffron threads, bay leaf, broth, and thyme and bring liquids to a boil over high heat. Cover the pan with lid or foil and reduce heat to simmer.
In a separate nonstick skillet, over medium high heat brown chicken on both sides in 1 tablespoon extra-virgin olive oil, 1 turn of the pan. Season chicken with salt and pepper. Add peppers and onions to the pan and cook 3 minutes longer. Add chorizo to the pan and cook 2 minutes more. Remove pan from heat.
After about 13 minutes, add shellfish to the rice pan, nesting them in cooking rice. Pour in peas, scatter lemon zest over the rice and seafood, then cover the pan again. After 5 minutes, remove cover or foil from the paella and discard any unopened mussel shells. Stir rice and seafood mixture and lift out bay and thyme stems, now bare of their leaves. Arrange cooked chicken and peppers, onions and chorizo around the pan. Top with parsley and scallions. Serve with wedges of lemon and warm bread.