Oliebollen are traditional Dutch New Year's Eve dough balls made by deep-frying batter.
The name literally means “oil balls.” The batter commonly contains flour, yeast, eggs, milk, and sometimes raisins or currants. Portions are dropped into hot oil, then served warm, usually with powdered sugar.
Oliebollen are especially associated with the period around New Year's Eve and New Year's Day in the Netherlands and parts of Belgium. Street stalls and temporary seasonal stands often sell them during the winter holiday period.
They are sometimes compared with doughnuts because both are fried sweet foods, but oliebollen are typically irregularly shaped and made from a yeast-based batter. Poffertjes are small, puffed pancakes, while bitterballen are savory croquettes, so neither is the traditional answer.