Preheat oven to 375°F (190°C) and line a baking sheet with parchment paper.

1. If using, soak raisins in rum or warm water for 10–15 minutes, then drain.
2. In a large bowl, toss sliced apples with lemon juice, granulated sugar, brown sugar (if using), cinnamon, nutmeg, raisins, and chopped nuts. Let sit to release juices.
3. On a clean kitchen towel, lay out one sheet of phyllo dough and brush with melted butter. Repeat layering 5–6 more sheets, brushing each with butter.
4. Sprinkle breadcrumbs evenly over the top layer to help absorb moisture.
5. Spoon the apple mixture in a line along one edge of the phyllo, leaving space around the edges.
6. Use the towel to gently roll the dough over the filling into a log shape, tucking in the ends as you go.
7. Place the strudel seam-side down on the prepared baking sheet and brush the top with remaining melted butter.
8. Bake for 35–40 minutes, or until golden brown and crisp.
9. Let cool slightly before dusting with powdered sugar and slicing to serve.