How to cook
Stir together the butter, sugar, milk, eggs, vanilla and salt. Add the yeast and knead the ingredients well. Gradually add the mixture to the flour and knead a soft dough that is not sticky (if necessary, add more flour).
Allow the dough to rise, then roll it out into a sheet with a thickness of 1/2″ (1 cm). Cut out rings using a glass and fry them in highly preheated oil. Drain the cooked donuts on paper towels. Fill them with jam using an icing piping syringe.
Serve them sprinkled with plenty of powdered sugar.