Stollen is also "a rich yeast bread containing reaisins, citron, and chopped nutmeats. [German, prop, support, stollen. See stull]

Stull-1. A supporting timber or other prop in a mine. 2. A platform braced against the sides of a working area in a mine. [probably from German Stollen, frim Middle High German stolle, prop, support, from Old High German stollo."

Source: The American Heritage Dictionary of the English Language - Third Edition