Hotbox

We made a hundred pizzas with a variety of toppings and put them in hotboxes — portable sterno heaters.

Source: wiktionary

A hotbox is made from two nonflammable, insulated bags ( resembling mini beanbags ) and works like this: you place semi - cooked, hot food into the hotbox and the retained heat will complete the cooking process .

Source: wiktionary

They collected the food – each meal on two covered tin plates and the whole lot contained in large metal hotboxes – from the old people's home, Wisteria Lodge.

Source: wiktionary

First, in the early 1860s, he dabbled with hotboxes—simple devices that used a wooden box with a glass lid to trap heat from the sun.

Source: wiktionary