Preheat your oven to 180°C (350°F) and grease a baking sheet with butter or line it with parchment paper.
Peel, core, and thinly slice the apples. Place them in a large bowl and add the breadcrumbs, sugar, cinnamon, raisins (if desired), and chopped nuts. Mix everything together until well combined.
Lay out one sheet of filo pastry or strudel dough on a clean surface. Brush it lightly with melted butter. Repeat this process with 2-3 more sheets, stacking them on top of each other.
Spread the apple filling evenly along one edge of the pastry, leaving a small border. Carefully roll up the pastry, tucking in the sides as you go, to form a neat log. Place it seam-side down on the prepared baking sheet.
Repeat steps 3 and 4 with the remaining pastry sheets and apple filling until you've used them all.
Brush the tops of the strudels with the remaining melted butter. This will help them brown and become crispy.
Bake the Apfelstrudels in the preheated oven for about 30-35 minutes, or until they are golden brown and the apples are tender.
Once baked, remove the strudels from the oven and allow them to cool slightly. Dust them with powdered sugar before serving.
