If you're already in the habit of cooking moroccan food, you probably know that it's easy to build on a number of basic recipes to add vegetables, beans or other ingredients or to adjust and experiment with seasoning, such as adding a little smen or perhaps some ras el hanout. Here, however, the same starting tagine gets dressed up with an oft-overlooked spice. Nigella seeds, also known as black seeds (or sanouj in moroccan arabic), impart a light oregano-like essence to this classic moroccan chicken tagine. Saffron, ginger and white pepper lend fragrant seasoning. Cinnamon and preserved lemon are optional, as are red olives. The cooking time is for preparation in a traditional clay or ceramic tagine. The time will be reduced by one hour if cooking in a conventional pot. The meal is traditionally served directly from the tagine or on a communal plate, with each person eating from his own side of the dish. Serve moroccan bread for scooping up the chicken and sauce.