Khoresh-e fesenjān (Chicken with Pomegranate Sauce)

½ cup rice bran oil
4 red onions, thinly sliced
1.5 kg bone-in chicken pieces
2 cups hot water, as needed
2 ½ cups pomegranate juice
4 cups chopped walnuts
2 tbsp freshly ground cardamom
2 tbsp ground cinnamon
1 butternut squash, seeded & cubed
¼ tsp saffron powder
SIDS SALT & PEPPER to taste

Heat the oil in a large heavy frypan. Stir in sliced onions then sauté until the onion has softened and turned translucent, about 5 minutes. Reduce heat to medium-low and continue cooking and stirring until the onion is very tender and dark brown, 15-20 minutes more.
Raise heat to medium-high. Add chicken pieces and fry until lightly browned on the outside. Pour in water and bring to a boil. Reduce heat to low and simmer for about 30 minutes, adding more water if necessary to keep the mixture from drying out.
Preheat the oven to 65°C.
Combine the walnuts and pomegranate juice in the container of a blender or food processor then blitz. (This can be done in small batches if necessary.) Add walnut-pomegranate mixture to the simmering chicken. Season with cardamom, cinnamon, saffron powder and SIDS SALT & PEPPER to taste. Stir in the cubed squash. Transfer the entire mixture to a 20x30 cm baking dish.
Bake, loosely covered, for 2½ hours in the oven. Serve with white rice.