Lightly flatten the chicken thighs with a mallet. Combine the olive oil, sumac, allspice, cardamom, white pepper and minced garlic in a prep bowl and whisk.
Place the chicken thighs in a large baking dish in a single layer and pour the olive oil marinade over the chicken. Cover and marinate in the refrigerator for at least an hour. I prepped the chicken mid-morning.
Once the chicken has marinated, preheat oven to 400 degrees and BAKE for 30 minutes.
Meanwhile, as the chicken bakes, chop the onions. Heat up 2 tablespoon olive oil in a pan and sautè the onions for about 10 minutes until they glisten and are just on this side of caramelized. Set aside.
In the same pan on medium-low heat gently brown the pine nuts in 1 tablespoon olive oil. Set aside.
Heat oven to BROIL.
Slice the bread loaves in half and layer the pieces singly-cut side UP on the bottom of an *oiled baking dish. I also lightly oiled the bread pieces on both sides. It doesn't have to be perfect as long as the bread pieces are singly layered. Tip: After layering the Arabic bread in the baking dish I lightly crisped the bread for 10 minutes in the oven along with the chicken as it baked.
Spoon HALF of the onions evenly over the bread slices. Slice the chicken thighs into medium-large chunks and place them top of the onions. Now place the other half of the onions on top of the chicken pieces. BROIL the musahkan for approximately 5-10 minutes.
After removing from the oven, garnish with the toasted pine nuts and if desired, with some fresh flat leaf parsley. Serve immediately with plain yogurt on the side.