Heat the oil in your skillet and start to brown the onion. After five - eight minutes, add the eggplant, garlic, spices and poppy seeds and cook for another five minutes. Add the marmite and chopped tomatoes then bring to boil. Reduce heat to a simmer, then add your diced chicken, allow to cook for 20 minutes uncovered before adding the artichoke hearts. Continue to cook on a low light until the chicken is fully cooked (at least 20 minutes longer).