For the batter, crumble and dissolve the yeast in 100 ml (approximately ½ cup) warm milk. Add about 150 g (approximately 5 ounces or ¾ cup) flour into a large bowl and make well in the center, add in the yeast mixture, dust with flour, cover and leave for 20 minutes.
Now add in the eggs, egg yolks and sugar to the flour and yeast mixture and mix with an electric mixer. Add in the remaining milk and the remaining flour, and knead until a smooth dough is formed. Add in the butter, salt and vanilla, and knead well. Cover and let rest at room temperature for 30 minutes.
To make the donuts, divide the dough into 20 portions and shape each portion into round ball. Place each ball on a lightly dusted worktop, flatten slightly with the palm of your hand and cover with a cloth. Let the donuts rise again until the volume has increased by three quarters.
Heat the frying oil to 170 degrees and fry the donuts in portions for 2 minutes, flip and fry again for 2 minutes. The donuts are nicely fried if they have a white ring around the center.
Place the finished donuts on a paper towel and immediately dust with sugar. Pour the apricot jam into a pastry bag with fine, long hole at the tip. Serve the donuts with jam.