Pile the flour into a kind of volcano on the table, put the egg in the hollow, distribute the other ingredients on the edge of the volcano. Cut the butter / margarine into flakes. Now you have to knead quickly, because if the dough gets too warm, it will not stay firm, but will fall apart again and again. Let rest for half an hour in a cool place.
While the dough rests, peel the apples and cut into cubes.
For the crumble, all the ingredients are put in a bowl and kneaded so that they disintegrate, which happens by itself.
Spread the shortcrust pastry on a greased baking sheet and cover with apple cubes. Put the streusel on top and cover with flakes of butter.
Bake on medium heat (200 °) for about 20-30 minutes.
My friends are thrilled and always argue about the last pieces!