Rub all pieces of chicken with a mixture of salt, pepper and cumin. Let stand for 1 hour.
In a separate saucepan, cover the prunes with cold water and add the cinnamon. Bring to a boil, reduce heat and simmer for 10 -30 minutes depending on dryness of prunes.
Steam the onions in the casserole with the turmeric, saffron, ginger, salt, pepper and ¼ cup of water for 15 minutes.
Meanwhile brown the almonds in a saucepan with oil and drain onto paper towels.
Using the same oil and pan, brown chicken on all sides then transfer to the steamed onions and add 1 cup water. (this can be transferred into the tagine at this point and placed in oven ). Cover and simmer for 30 minutes.
Add the cooked prunes and some of the prune water to the tagine and continue cooking until the chicken and prunes are really tender.
To serve, place chicken pieces on a serving dish (or simply leave in the tagine). Cover with prunes and sauce, then sprinkle with almonds and sesame seeds (if desired).