Crumble the yeast, add a teaspoon of sugar, and pour in about 200 ml of lukewarm milk - mix thoroughly - cover with a cloth and set aside in a warm place for about 20 minutes - so that the yeast starts to work.
15 g yeast, 1 teaspoon of sugar, 200-240 ml milk
In a large bowl, place the flour, egg, melted and cooled butter, and sugar.
375 g wheat flour, 1 egg, 50 g sugar, 30 g butter
Add the yeast starter and knead the dough - if it's too thick, add more milk.
Cover the bowl with the dough with a cloth and set aside in a warm place for about an hour - for it to rise.
After rising, briefly knead the dough again, place it on a lightly floured surface, and roll it out to a thickness of about 1-1.5 cm.
Cut out donuts with a glass or a round cutter (my cutter had a diameter of 7 cm) and place the discs on a baking sheet (keep space between the donuts).
Knead the remaining dough again, roll it out, and cut out donuts - repeat until all the dough is used.
Cover the baking sheet with the donuts with a cloth and set aside in a warm place for about half an hour.
Preheat the oven to 180 degrees Celsius (top-bottom mode), place the donuts, and bake for about 10-12 minutes - until a nice golden color.
After baking, remove from the oven.
Transfer the jam to a piping bag (or a bag with a long nozzle) - if the jam has large fruit pieces, it's a good idea to blend it beforehand.
Make a small incision in the donuts with a narrow knife and fill with jam.
Finally, sprinkle the donuts with powdered sugar.
Uwagi
If you don't have a way to fill the donuts after baking, you can bake them with the filling right away. Gently stretch a cut piece of dough in your hands, place a teaspoon of filling (preferably preserves) in the center, and then carefully seal the dough. Set the donuts aside to rise slightly, then bake them for about 15 minutes. After baking, let them cool and sprinkle with powdered sugar.Enjoy!