Heat oven to 190°C. Heat oil in an 7.6L Dutch oven over medium-high heat. Season chicken with salt and pepper; add to pot and cook, turning, until browned, 12 to 15 minutes. Transfer chicken to a plate. Add onions to pot; cook until golden, 10 to 12 minutes. Add spices; cook for 2 minutes. Return chicken to pot with stock; boil. Bake chicken, covered, until tender, 35 to 40 minutes. Stir in olives, butter, parsley, cilantro, and lemons into pot, and cook for 6 minutes. Serve with rice or flatbread.