Here is a quote from Wikipedia. In case you ever wondered why reformation was inevitable. You know it was not about religion - but about butter, really! =)
The early Stollen was a different pastry, the ingredients were very different - flour, oats and water.
As a Christmas pastry, Stollen was baked for the first time at the Saxon Royal Court in 1427, and was made with flour, yeast, oil and water.
The Advent season was a time of fasting, and bakers were not allowed to use butter, only oil, and the cake was tasteless and hard.
In the 15th century, in medieval Saxony (a region in the eastern part of Germany, north of Bavaria and south of Brandenburg), the Prince Elector Ernst (1441 - 1486) and his brother Duke Albrecht (1443 –1500) decided to remedy this by writing to the Pope in Rome. The Saxon bakers needed to use butter, as oil in Saxony was expensive and hard to come by, and had to be made from turnips, which was unhealthy.
Pope Nicholas V (1397 – 1455), in 1450 denied the first appeal. Five popes died until finally, Pope Innocent VIII, (1432 – 1492)  in 1490 sent a letter to the Prince, known as the "Butter-Letter" which granted the use of butter (without having to pay a fine) - but only for the Prince-Elector and his family and household.
Others were also permitted to use butter, but with the condition of having to pay annually 1/20th of a gold Gulden to support the building of the Freiburg Minster. The ban on butter was removed when Saxony became Protestant.
Over the centuries, the cake changed from being a simple, fairly tasteless "bread" to a sweeter cake with richer ingredients, such as marzipan, although the traditional Stollen is not as sweet, light and airy as the copies made around the world."
During Advent I like to bake a few batches of Stollen loaves to give to some special people who have made my life better over the year.
It usually takes me a whole day to bake a couple of loaves, since there are so many steps involved. As we say in German: Gut' Ding will Weile haben!" In translation: All good things take time. Stollen are made with yeast. Yeast means rising time. Rising means waiting. It's a good way to celebrate Advent. After all it's about waiting, right? There are so many different steps involved. I was going to post a recipe here. But since this post is so lengthy already I shall have to make you wait. It's Advent after all! LOL