In a large pot, combine the pearl barley or wheat berries with 4 cups of water or chicken broth. Bring to a boil, then reduce the heat to low and simmer for about 45 minutes to 1 hour, or until the barley is tender and most of the liquid is absorbed.
In a separate pot, combine the chicken thighs or drumsticks with enough water to cover them. Bring to a boil, then reduce the heat and simmer for about 30 minutes, or until the chicken is cooked through and tender.
Remove the chicken from the pot and let it cool slightly. Shred the meat, discarding the bones, and set aside.
In a large skillet, melt the butter over medium heat. Add the finely chopped onion and sauté until soft and translucent. Add the minced garlic and cook for another minute.
Add the cooked barley and shredded chicken to the skillet with the onions and garlic. Stir in the ground cinnamon, ground allspice, salt, and pepper. Mix well and cook for another 10-15 minutes, stirring occasionally, until the flavors are well combined and the mixture is heated through.
Transfer the harissa to a serving dish and garnish with freshly chopped parsley. Serve hot.
Enjoy your meal!