A duivekater was a traditional diamond-shaped bread eaten on religious holidays, mainly Christmas. It was often highly decorated.
I have sometimes come across the term in deacons’ accounts where poor children were given them as a gift. They can also be seen on various paintings from the 1600s. It is not a common word but a fun one to learn on Christmas day.

A baker and his wife, 1658. The upright decorated bread is a duivekater. Credits: Jan Steen, collection Rijksmuseum (public domain)