Back in the '70's it was called cloud bread. But Rev rolls might even be older.

I make mine with ground flax, almond flour and ground pork rinds (no cheese).

I also make a hamburger bun by lightly beating one (whole) egg, adding a tablepoon of each of ground flax, almond flour, and ground pork rinds and frying it up into 2 little pancakes. Since it has egg, pork and beef (from the burger) I call it my Barnyard Burger.