In the same skillet, soften the sweet potato and onion for 5 minutes. Add the garlic and spices. Cook for 1 more minute while stirring. Add the tomatoes, ½ cup (125 ml) of the broth and the olives. Season with salt and pepper. Mix well. Return the chicken to the skillet. Cover and simmer for 5 minutes or until the chicken is cooked through. Adjust the seasoning. Reduce the sauce slightly, if desired.