An oven for treating food including a well of sheet metal material that is open at the top, a removable insert open at the top end located in the well, the side walls and bottom of the insert being spaced from the side walls and bottom of the well to define air circulating passages therebetween with the top of the circulating passages being open. The insert also includes a plurality of gill openings formed in the side walls of the insert, the gill openings having the open portion thereof facing upwards on the outer side of the insert to divert air from the air passages into the interior of the insert. The insert further includes openings at the bottom thereof for communicating the air passages with the interior of the insert. The oven further includes a removably fitted lid which forms the top thereof, and an air circulating fan depending from the lower side of the lid for drawing air upwardly out of the insert. The fan serves to propel air laterally to the open top of the air passages for circulation downwardly through the air passages for entry into the interior of the insert for circulation over an object that is to be heated. An electrical heater is mounted on the lower side of the lid for heating air circulated by the fan.