Rinse and thoroughly pat dry the chicken parts. Sprinkle them liberally with salt and fresh ground pepper. In a large sauté pan, over medium-high flame, combine butter and olive oil and heat until butter has melted. Brown the chicken in two separate batches. Remove chicken from the pan. Lower flame to medium and add sliced onion and ginger. Saute for 8 minutes, stirring frequently. Chop 20 olives and add to the onion and ginger mixture. Saute for 1 minute. Add flour, cumin, cayenne pepper and cinnamon and cook for another minute, stirring constantly. Add the chicken broth, lemon juice and dates, scraping the pan to loosen browned bits. Bring to a slow boil and return the browned chicken to the pan. Cover and reduce heat to a simmer. Continue cooking for another 45 minutes and serve over prepared rice.