In a bowl and add cumin, za'atar, sumac (or grated lemon zest), black pepper and salt. Add the melted butter or oil and mix.Gently rub this onto the spatchcock chicken.
In a large roasting dish, place the garlic and onions on the bottom, season and place the spatchcock chicken on top.
Pour the stock and wine into the roasting tray and transfer the pan to the oven and cook for 45 minutes or until done and golden brown.Approx. 10 mins before the chicken is done, add the orzo. You may to add some more water if there isn't enough liquid. Serve.