Gratin Dish from Gense. With this gratin dish made of cast iron you can cook as a professional. Cast iron is an unbeatable material when it comes to cooking, as it spreads and keeps the heat. The gratin dish is burned in rapeseed oil, and therefore requires minimal use of grease. It can be used on both traditional stoves and induction cooktop. Should only be cleaned with water and oiled with cooking oil if necessary.