Today I converted two people to the Cult of the Rotisserie Cake, or Drehspießkuchenkult, and drafted a new image. It has no bottom, so batter drips fall and be caught and reused. It's made of refractory cement, electrically heated (optimally), and has extra space on the top to accommodate a ladle full of batter. Refractory cement definitely seems like the best solution. Way better than steel. Though a steel skin on the outside is good.