In a large bowl, combine 1/4 cup olive oil, the coriander, cumin, paprika, cinnamon, saffron, cloves, ginger and red pepper flakes. Sprinkle the chicken with salt and pepper and place in the marinade. Stir until the marinade covers each piece. Refrigerate for 2 hours and up to overnight.
Remove the chicken from the marinade and pat dry; reserve the marinade. Heat the remaining 2 tablespoons olive oil in a tagine or a large Dutch oven. Place the chicken skin-side down in the pot and brown for 4 to 5 minutes. Turn and brown an additional 3 to 4 minutes. Remove the chicken and reserve on a plate.
Add the onions and garlic to the same pot and saute until tender, about 5 minutes. Add the chicken stock, green olives, lemon peel, 1/4 teaspoon black pepper and the reserved chicken and marinade. Bring to a low boil and reduce the heat to a simmer. Cover and cook 45 minutes.
Stir in the cilantro, parsley and lemon juice. Serve with couscous if desired.