Home bakers, confectioners and factories bake many tens of millions of oliebollen for every turn of the year. This successor to the 'oliekoeck' has been the traditional delicacy around old and new since the nineteenth century.
Why do we eat oliebollen every year on New Year's Eve, even more than apple turnovers? There are several theories. According to one story, it has to do with the fatty pasta that the Batavians and Frisians offered to the Germanic goddess Perchta in the period between December 26 and January 6. The fatty food would make the goddess's sword slip on the bellies if she tried to cut them open.
Another theory is based on an ancient Lent period. In the Middle Ages, people fasted between Saint Martin (November 11) and Christmas. They did this partly to save the stock they had built up for the long winter. At the end of that period there was then partying, drinking and eating. Oil cakes were an important part of that feast, made of non-perishable ingredients, rich in fat and calories and therefore good fuel against the winter cold. But perhaps there is also a connection with a late medieval custom to treat the poor around New Year's Eve to a flat wafer or oliekoek.
It was not until the nineteenth century that the oliekoek acquired the status of the delicacy of old and new. It is unclear when and why the oliekoek became oliebol. It had to do with other ingredients and techniques (such as frying), which allowed bakers to bake more lightly. It was not until the twentieth century that the name oliekoek disappeared. The oliebol, on the other hand, has never left.