Baking in a box. Take moderate-sized box, we usually used one the size used to deliver copier paper came in (24cm x 24cm x 48cm or so). Line the inside of the box and the lid with aluminium foil (staples are a good way to attach it to the lid.) Put some stones or a tile on the bottom, both to hold down the box and to protect it from the coals. Run a few coat-hanger wires through about 2/3 of the way up to form a rack.
Light charcoal (this needs adult help or supervision), putting about 10 briquettes in an pan. The pan goes in the bottom of the box. When the lid is on the box, the air inside it will get to about 300-350 F (150-200C) which is well below the ignition temperature of paper, but more than hot enough to bake with. A small tray with cookies or biscuits can go on the rack and after a few minutes will be baked. Since the temperature depends on how well the lid seals (there has to be some leakage to keep the coals burning, but this isn’t usually a problem), the exact baking time and temperature will vary.
Still it’s good fun, requires little advance preparation, and can be put together by 8-11 year old children without much assistance from mom or dad. Beats an “easy-bake” any day.