A jelly doughnut has what kind of filling?

A jelly doughnut has a fruit preserve filling.

The preserve may be called jam or jelly, depending on regional terminology. The doughnut is typically made from sweet, yeast-raised dough, fried, and filled after cooking by piping fruit preserve into its center. Common flavors include raspberry, strawberry, cherry, and plum.

The German Berliner is one of the best-known versions. A printed German cookbook from 1485 contains an early recipe for a jam-filled fried pastry called Gefüllte Krapfen. As sugar became more widely available, fruit fillings became increasingly common in European pastries.

Jelly doughnuts are easily confused with cream- or custard-filled doughnuts, which are also common. Regional versions include Polish pączki, Jewish sufganiyot, Italian bomboloni, and Southeast European krafne; their fillings and toppings can vary, but fruit preserve remains the defining filling of the standard jelly doughnut.