The wet-bottom version is set like cake at the top where it was mixed in with the crumbs, but the very bottom is a stickier, gooier custard-like consistency.

[3] In the 1880s, home bakers added a crust to make it easier to eat alongside a cup of coffee in the morning, without plates and forks.

[2][9] The mule, in turn, may have been named after a song that became popular half a century before: "Shoo Fly, Don't Bother Me".

[10] In the Pennsylvania Dutch language, shoo-fly pie is called Melassich Riwwelboi or Melassichriwwelkuche[11] (molasses crumb cake).

[12] Before its modern name became popular during the 20th century, it was molasses crumb pie or soda rivvel cake (rivels are lumps of food).