The present invention relates to a cooking device (1) that provides cooking by the sous-vide method realized by placing the foods in vacuum bags and cooking in heated water at low temperatures for a long period of time, comprising an oven cavity (2) enabling the vacuumed foods to be placed into the device (1), a level sensor (7) that detects the change in water level inside the oven cavity (2), and a control unit (6) that determines the food core temperature, the water temperature and the cooking steps required for the food to be cooked according to the type and amount of food.