- Whisk together the sugar, butter, milk, vanilla, salt, and eggs. Whisk in the yeast.
- While stirring constantly, add the flour ½ cup at a time until the mixture is a firm dough.
- Knead the dough for about 5 minutes. Put it back in the bowl, cover, and let it rise until it's twice its original size—this should take about 1½ hours.
- Pat the dough on a lightly floured board, and roll the dough until it's about ½ inch thick. Cut out little rounds. You can roll the excess dough again to make more pączki.
- Let the dough rounds rise for about 30 minutes or until they've doubled in size.
- Heat enough oil to about 350°F, then deep fry the pączki until they're golden-brown. Let cool.
- While the pączki cool, spoon some fruit jelly or jam in a pastry bag with a long point. Poke the pastry bag in the sides of the pączki, and fill them.
- Sprinkle some powdered sugar on top and enjoy!