Heat oil in a 6- to 8-qt. heavy-bottomed pot over medium-high heat.
Add half chicken, skin side down, and cook until golden brown, 5 to 7 minutes. Turn over and cook 3 minutes more.
Transfer to a plate; repeat with remaining chicken and set aside.
Drain all but 2 T. oil from pot and reduce heat to medium.
Add onion and sauté until golden, 5 to 7 minutes.
Add garlic and ginger and cook stirring constantly, for 3 minutes.
Add cinnamon, turmeric, coriander, black pepper, cardamom pods, chilies, and salt and stir to combine.
Return chicken to pot and add apricots, prunes, 2 cup chicken broth, and parsley sprigs. Bring mixture to a boil, then reduce heat to medium-low. Cover and simmer 40 minutes.
Take pot off heat and remove parsley sprigs and chilies.
Remove skin from chicken.
In a covered medium saucepan, bring remaining 2 cups chicken broth to a boil. Turn off heat, stir in couscous, cover, and let sit 5 minutes.
Uncover pan and fluff couscous with a fork.
Stir in 2 tablespoons minced parsley, pine nuts, and lemon zest and toss to combine. Mound couscous on a platter. Top with chicken thighs and pour sauce over the chicken. Sprinkle with remaining 2 tablespoons parsley.