In a large saucepan, warm the oil over medium heat. Add the onion and saute, about 8-10 minutes until softened. Meanwhile, place the garlic and spices (cinnamon through salt) in a small bowl. When the onions are soft, dump in the garlic and spices and cook for a minute.
Add the chicken and cook a few minutes, turning. If the onions and spices start to stick, pour in the broth and scrape up the bottom. If not, then just pour it in after the chicken has been cooking a few minutes per side. Partially cover, turn heat to low, and let it simmer until the chicken is just cooked through, about 15 minutes. While the stew is simmering, make the couscous according to package directions.
Remove the chicken and place on a plate. When cool enough to handle, shred the meat and add it back to the pot with the squash, prunes, and olives. Cook another 12-15 minutes over gentle heat until the squash is cooked through. Taste for seasoning and add more salt and pepper if necessary. Ladle into bowls and add the herbs, serving with couscous or bread if desired.