Russian Mennonite zwieback, called Tweebak in Plautdietsch, is a yeast bread roll formed from two pieces of dough that are pulled apart when eaten.

Traditionally, this type of zwieback is baked Saturday and eaten Sunday morning and for afternoon Faspa (Standard German: "Vesper"),[1] a light meal.

[2][3] This zwieback originated in the port cities of the Netherlands or Danzig, where toasted, dried buns were used to provision ships.

Mennonite immigrants from the Netherlands, who settled in around Danzig in West Prussia continued this practice and brought it to Russia, when they migrated to new colonies in what is today Ukraine.

[1] Traditionally, zwieback are made using lard instead of butter or a mixture of the two.