Grate the apple and mix with the rest of the ingredients. Depending on your preference, you can use more or less oat flakes for the consistency. That certainly always depends on the size of the apple, how thin or sticky the dough will be, which is why I have omitted the oat flakes in grams.
Bake small round donuts in a little oil or butter in a pan on both sides until they are golden yellow.
I also tried the recipe without yogurt, but then found the Krapferl too dry. Could also imagine vanilla sauce or applesauce as a side dish if necessary.