Take butter out of the fridge an hour before cooking; let it soften and become manageable.
Before combining ingredients for the dough, slightly warm up the milk. Add dry yeast, a pinch of salt and amount of sugar that is mentioned in the list. Thoroughly stir to combine all the ingredients so that sugar and yeast dissolve a little in milk. Set the mixture aside for 10-15 minutes for yeast to activate.
Sift flour through a fine sieve into the milk; next beat an egg and add butter to the mixture.
First, stir the mixture with a spoon and then knead the dough with hands until you have thick but soft and tender dough. Let the dough sit for 60 minutes covered in a bowl before deep-frying. After a while, the dough will rise approximately twice its size.
Sprinkle the surface with some flour before rolling dough. Divide the dough into several even pieces to get the layer 5 mm thick. Cut doughnuts with a doughnut cutter (you can also use biscuit cutters of two sizes).
Heat oil in a deep saucepan. Lower doughnuts into a hot oil (use a slotted spoon for the purpose not to get burned) and fry them until golden. It should take 2 minutes for each side and you better fry them in bunches by 2 or 3 pieces. Let the oil reheat between each batch of doughnuts.
Drain fried donuts on the paper towels to get rid of excess oil; sprinkle doughnuts with some powdered sugar before serving. Bon appetite!