Wikipedia
Donauwelle
Donauwelle (lt:Danube wave) is a traditional sheet cake popular in Germany and Austria. It's a pound cake with sour cherries, buttercream, cocoa and chocolate and like a Marble cake bright and dark cake batter are mixed into each other to create swirl effects.
Due to its wavy pattern inside and its chocolate decoration that resembles waves it got its name although the derivation of the term "Donau" is not clear. It could be a hint to the prevalence of the cake that is popular in those states that the river Donau flows through .
Another name is Schneewittchenkuchen which means Snow-White-Cake and gives credit to the colour combination black, white and red that is also mentioned in the fairy tale of Snow White.