The standard issue mess kit for the Wehrmacht in 1944-45 was two-piece, either steel or aluminum constructed, and designed to fit tightly together. This way the kit could used to transport food for future consumption.
The lower "bail" section was used for soups and the top part as a plate for more solid foods.
Both sections of the kit could be used for cooking or warm ups, as well as the cup from the German canteen. These could be placed on a portable fold out Eisbit ration heater.
As shown in the top of the above photo, when not in use the Eisbit ration heater folded into a compact size for transport. The unit was fueled by tablets, similar to wood pellets.