In a large soup pot or Dutch Oven, heat the olive oil over med-high heat. Add the onion and cook until soft and translucent, about 2 minutes.Add the diced carrot and celery and 1 tablespoon of the chermoula paste and stir until the vegetables are evenly coated. Add the stock and the chicken breasts to the pot. Bring to a boil, then reduce the heat to medium, cover and let simmer until the chicken is cooked through, about 6-8 minutes.
Using a slotted spoon, transfer the cooked chicken to a plate and set aside until cool enough to handle. Once cooled, shred or cut into bite-size pieces.
Add the chickpeas and the Israeli / pearl couscous to the pot. Return to a boil, then reduce heat to a simmer, cover and cook until tender, about 10 minutes.
Add the shredded chicken to the pot and stir in 2-3 tablespoons of the chermoula paste.