Armenian pearl barley and chicken stew (harissa)

Drain pearl barley and rinse under cold running water. Place in a large saucepan, cover with 2.5L water and bring to the boil. Reduce heat to medium and cook, adding more water if necessary, for 2½ hours or until water is absorbed and barley is very soft; don’t stir too often as this will cause barley to stick to the pan.
Halfway through pearl barley cooking, place the chicken in a stockpot and cover with water. Bring to the boil, skimming any impurities that rise to the surface, then reduce heat to medium and cook for 1 hour or until chicken is cooked through and starting to fall apart. Remove chicken from water and reserve 1.5L stock. When chicken is cool enough to handle, using your fingers, finely shred the meat, removing and discarding the skin and bones.
Add shredded chicken and 1L reserved chicken stock to the cooked pearl barley. Place pan over low heat and cook, stirring occasionally, for 20 minutes or until thick. Blend with a handheld blender until the consistency of fine porridge; add more of the reserved 500ml stock if necessary to achieve the desired consistency. Season with salt, white pepper and cumin.
Just before serving, melt butter in a small pan and cook until a nut-brown colour. Pour over harissa. Serve with extra cumin and the berbere sprinkled over.