A pączek is the Polish filled doughnut traditionally associated with Fat Thursday.
Pączki are deep-fried pieces of especially rich yeast dough. Traditional fillings include rose-petal jam, plum jam, or other fruit preserves, and modern versions may contain custard, cream, or chocolate. They are commonly glazed or dusted with sugar.
In Poland, pączki are strongly linked with Tłusty Czwartek, or Fat Thursday, the last Thursday before Lent. The day is associated with eating rich foods before the Lenten fast, and bakeries produce large quantities of pączki for the occasion.
The singular form is pączek and the plural is pączki. In English-language contexts, “paczki” is also common, but the Polish spelling uses the letter ą. Pączki are related to other European filled fried pastries but have their own Polish culinary and holiday tradition.