In a food processor, grind the walnuts until they resemble sand. Then transfer to a large pan and dry toast them for 10-15 minutes, stirring constantly to make sure they do not burn. Remove from the pan and set aside.
Heat the cooking oil in a large pot over medium heat. Add the onions and cook until golden, about 8 minutes. Add the turmeric, pepper, and toasted walnuts. Saute for a few minutes, then add the 2.5 cups of chicken broth. Cover and cook on a low simmer for 20 minutes, stirring occasionally while you prepare the chicken. If the stew starts to look dry, add ¼ cup hot water or broth.
Meanwhile, in a large skillet, season the chicken with salt and pepper. Brown the chicken on both sides. Set aside.
To the walnut mixture, add the pomegranate molasses, saffron water, prunes, and the remaining chicken broth, adding more than the recipe suggests if the stew appears too dry. Keep the heat on low and simmer for 30 minutes.
Add the chicken to the pot and cook for a minimum of 20 minutes, or more, making sure that the stew does not stick to the bottom of the pan. Taste and adjust the seasoning, adding an additional 1-2 tablespoons of pomegranate molasses and salt if needed.
Serve with fresh basmati rice and enjoy.