Bring the chicken stock to the boil in a small saucepan, and turn off the heat. Add the salt, pepper, cumin, and saffron threads and allow to steep for at least 15 minutes.
Meanwhile, heat the olive oil and melt the butter in a saute pan. Add the courgette and cook for 5 minutes, or until lightly browned. Bring the chicken stock just back to a boil. Place the couscous in a large bowl and add the cooked courgette. Pour the hot chicken stock over them. Cover the bowl tightly with plastic wrap and allow to stand at room temperature for 15 minutes. Add the basil and parsley. Toss the couscous and herbs with a fork, and serve warm or at room temperature.