Abstract: A heating element is contained within a resealable heating bag. At least one degassing valve is embedded in the surface of the heating bag, providing for a way for steam to be released from the interior of the bag. The heating element comprises powdered aluminum, calcium oxide, calcium carbonate, calcium dihydroxide, sodium carbonate and sodium hydroxide that is reacted with water in a two stage chemical reaction to create heat within the heating bag. The element and the heat generated by the heating element is transferred to a packaged food item placed within the heating bag, thereby heating the food item to a desired temperature. The timing and the heat/pressure level of the cooking process inside the sealed bag can be controlled by correlating the interior space of the heating bag and the size of the element and number of degassing valves embedded in the surface of the heating bag.