Crumble the yeast, mix with lukewarm milk, add a little sugar and flour and let rise in a warm place. Then work with the other dough ingredients to form a smooth yeast dough, cover and let rise in a warm place until the dough has doubled in volume.
For the filling, toast the breadcrumbs in butter, peel the apples and cut them into flakes.
Roll out the dough about finger thick on a floured work surface and distribute the toasted breadcrumbs evenly on top. Cover with the apples, sprinkle with sugar, cinnamon and raisins. Roll up into a strudel, place on a baking sheet lined with baking paper and let rise again, then bake at approx. 180 ° C for about 40 minutes. When the strudel turns slightly brown on the surface, brush with melted butter and finish baking.