Mix garlic, saffron, ginger, paprika, cumin and turmeric together plus a 1/2 teaspoon Kosher salt. Add pepper to taste. Rub chicken with mixture, cover, refrigerate and marinate 3 hours to overnight
Heat oil in heavy skillet. Add chicken, and brown on all sides. Remove to platter. Add onions to skillet, and cook over medium-low heat about 15 minutes, until lightly browned. Transfer to tagine, if you are using one, or leave in skillet. If using add the cinnamon stick
Put chicken on onions. Scatter with olives. Quarter the lemons, remove pulp and cut skin in strips. Scatter over chicken. Mix stock with the lemon juice. Pour over chicken.
Cover tagine or skillet. Place over low heat, and cook about 30 minutes, until chicken is done. Scatter parsley on top, and serve