 The cakes (optionally sprinkled with sugar and cinnamon) are baked for about 15 minutes at 200-220°C, retaining an uneven form and contour.Variations include the Jamaican rock cake, which is similar, but usually includes grated coconut, and the traditional British rock cake, which contains oatmeal.Author Agatha Christie mentions rock cakes in her stories and novels, including "Three Blind Mice" and "The Murder at the Vicarage".