Combine the lemon juice, zest, olive oil, garlic, salt, pepper, cumin, paprika, coriander, turmeric, cinnamon, and red pepper flakes in a large bowl and whisk well. Add the chicken and toss to coat with marinade. Cover and chill 1 hour or overnight.
Preheat an oven to 425°F. Add the red onion to chicken mixture and toss to combine. Place in a roasting pan. Bake until browned and cooked through, 30 to 35 minutes, flipping the chicken a few times.
When almost done, dot with butter, and broil for 3-5 minutes to get nice crispy skin. Remove and discard the bones (they should slip out easily) and slice the chicken into strips, cutting against the grain. Shower with parsley and serve.
