Zwieback is a crispy, sweetened bread made with eggs and baked twice. It is sliced before it is baked for the second time, which then results in a crispy, brittle slice that closely resembles melba toast or rusk.
Although commonly used for teething children, it also makes a nice breakfast snack which one can use with butter, cream cheese, jelly and peanut butter for example.
Medicinally, Zwieback is very good for upset stomachs, as it absorbs acid. The Brandt Zwieback has a 99% name recognition in Germany; even more than Coke!