Set the oven to preheat at 180℃.
Prepare the spice mix by combining all the spices and salt into a bowl. Dice the onion into small pieces.
Make slits on the thick parts of the chicken using a knife. Coat the chicken lightly all over with some olive oil. Sprinkle half of the prepared spice mix onto the chicken and rub it thoroughly all over the chicken. Arrange the chicken onto a lined baking tray and bake it for 1 hour at 180℃, flipping half way.
While the chicken is baking, take a deep pan and add the diced onion into it. Add the olive oil and the remaining spice mix. Combine everything together and put it on medium low heat. Cook for 40 minutes, stirring occasionally.
Once the chicken and onion mixture are done, it’s time to assemble. Cut each flatbread into 8 triangles (like pizza). Take a big (flat) dish and put a layer of flatbread on the bottom. Spread the onion and olive oil mixture all over it, then arrange the roasted chicken on top (including any liquid released from the chicken).
Toast the pinenuts in a teaspoon of olive oil on medium low heat until it turns golden brown. Garnish the chicken with the toasted pinenuts, chopped parsley and sumac.