In a small sauté pan over medium heat, toast the spices, stirring frequently, until fragrant, about 3 minutes. Transfer to a large bowl. Add the bay leaves, 2 Tbs. of the olive oil, the garlic, salt and pepper and whisk to combine. Add the chicken and stir to coat. Cover with plastic wrap and refrigerate for 3 hours.
Remove the chicken from the marinade and reserve the marinade. In a tagine over medium-high heat, warm the remaining 2 Tbs. oil until almost smoking. Working in batches, brown the chicken on all sides, 5 to 7 minutes total. Transfer to a plate.
Add the onions to the tagine and cook, stirring, until soft and translucent, about 5 minutes. Reduce the heat to medium and add the chicken, reserved marinade, the 1/2 cup parsley, cilantro, lemon juice, preserved lemon and olives.
Cover the tagine and cook until the chicken is tender and falling off the bone, 1 to 1 1⁄2 hours. Discard the bay leaves. Garnish with parsley and serve the chicken directly from the Tagine. Accompany with couscous.