A pushcart for frozen confectionaries includes a wheel supported insulated cabinet defining a food storage chamber having a rectangular top opening covered by three pivotally connected and removable lid sections. A stainless steel cryogenic tank is supported within the storage chamber under the center lid section and includes an inner wall surrounded by an outer wall to define a closed space therebetween. The inner tank wall defines a cryogenic chamber for receiving liquid nitrogen, and the space between the walls receives a predetermined partial vacuum or gas for precisely controlling the heat transfer from the storage chamber through the tank walls for absorption by the liquid nitrogen. Nitrogen vapor escapes from the tank chamber into the storage chamber through nozzles to maintain a low pressure within the tank, and the tank may be lifted and removed from the storage chamber after removing the lid sections for interchanging cryogenic tanks with different heat absorbing rates and to facilitate cleaning the inside walls of the cabinet.