Earthen ovens have been used to cook food for at least two thousand years. They were widely used in homes and forts in the 18th century, they were moved from place to place on wagons in medieval times, and there is evidence of them being used all around the world during the era of the Roman empire.
They’re made from a mixture of clay and sand that hardens from the heat of the fire. The way it works is you build a fire inside of it, then remove the fire and use the residual heat to cook food. This way you can cook food slowly and evenly without worrying about burning it. Earthen ovens are great for baking bread or even pizza.
In the video below, Townsends shows you step by step how to build an earthen oven.