Step 1:
In a small skillet over medium heat, toast coriander seeds, stirring occasionally, until fragrant, about 1 minute. Transfer to a spice grinder or mortar and pestle and let cool completely, then grind.
Step 2:
Preheat oven to 350°F. Season chicken generously with salt; let stand. Meanwhile, zest orange. In a small bowl, combine 2 teaspoons orange zest with Aleppo pepper, thyme, coriander, and 1 tablespoon oil.
Step 3:
Rub spice mixture all over chicken; let stand at least 30 minutes, or refrigerate, covered, up to 2 days. Slice orange in half lengthwise, then cut one half crosswise into very thin slices and scatter in the bottom of a roasting pan, along with chickpeas and shallots. Squeeze juice of remaining orange half over chickpea mixture; toss with remaining 7 tablespoons oil. Season with salt.
Step 4
Place chicken in pan, skin-sides up; drizzle with oil. Roast until chicken is golden and very tender, and chickpeas and shallots are beginning to caramelize, 1 1/2 to 2 hours. Remove pan from oven and transfer chicken to a plate. Stir olives and greens into pan, then return chicken. Switch oven to broil and cook until chicken is golden brown and greens are just wilted, about 1 minute more. Serve.