Preheat oven to 350°F. Crush the saffron in the palm of your hand and add to a small bowl with 2 tablespoons warm water to bloom.
Use paper towel and pat dry the chicken. In a small bowl mix together the coriander, white pepper, turmeric and salt. Rub this spice mixture all over the chicken pieces and set aside.
Heat a tagine on top of a stove burner with a heat diffuser underneath or use a deep skillet without diffuser on medium heat (See Note 3). Add 1 tablespoon each olive oil and butter and brown the chicken pieces, skin side down first, for 3-4 minutes per side. Remove from tagine/skillet and set aside.
Add 2 tablespoons of olive oil and 2 tablespoons of butter. Sauté the onions and ginger. Cook for several minutes and add the chicken on top of the onion mixture, pressing down to nestle the chicken in between the onions.
Scatter the chickpeas and diced preserved lemon pieces over chicken. Sprinkle 2 tablespoons of the parsley, saffron water and 1 cup of chicken stock over all. Put tagine lid on, or lid to skillet, and place in the oven for 50 minutes (40 minutes for boneless chicken pieces).
Remove from oven and add the remaining 2 tablespoons butter, remaining parsley and olives. Stir and spoon juices over chicken. Cover and let rest for 5 minutes. Serve with couscous or steamed rice of choice.
Notes
I use both bone-in and boneless, skinless thighs, breasts and or legs. For the bone-in, cook in oven for the 50 minutes and 40 minutes for the boneless if using.
A Dutch oven or a heavy-bottomed pot with a tight-fitting lid can be used instead of a tagine for similar slow-cooking results.
You should not place a glazed clay tagine on a direct flame or it will crack and ruin the tagine.