Warm the milk in a small pot lukewarm and remove from the stove. Crumble the yeast into it and dissolve it while stirring. Put flour, butter in flakes, 100 g sugar, vanillin sugar, salt and eggs into a large mixing bowl.
Add the yeast milk and knead with the dough hooks of the hand mixer for about 5 minutes to a smooth dough.
Cover and leave to rise in a warm place for about 50 minutes. Then knead again briefly. Wash, peel and quarter apples, cut out the core and cut quarters into small cubes.
Knead under the dough.
Heat the oil in a wide saucepan, cut off the yeast dough with a tablespoon of doughnuts. Slide into the hot oil. Fry 4-5 doughnuts each while turning them golden brown. Lift them out and let them drip off a little on kitchen paper.
Process the remaining dough in the same way. Mix 100 g sugar and cinnamon. Turn the doughnuts and serve.