Place a clean sheet on your kitchen table and liberally flour it and rub the flour into the sheet.
Take your dough out of the fridge and begin stretching it into a rectangle, thinning out the center of the dough and bringing it to the outer edges.
Then take two fists and start to stretch the dough in the same way that pizza dough is stretched.
Place your rectangle of dough onto your sheet and use a rolling pin to thin out the dough and roll it into an even rectangle.
Carefully place your hands under the dough with your knuckles facing upwards and use your knuckles to stretch the dough towards the edges of the table, taking care to stretch from the center of the dough and bring it towards the edges. Stretch the dough first the width of the table and drape the it over the edges. Once you've stretched the dough width-wise, concentrate on stretching it length-wise. It will take time and patience to stretch it as thinly as possible. It's said that it should be so thin that you can read a newspaper through it.
Once the sides have been draped over the edge of your table (or at least three sides of your table), use scissors to cut off the thick, hanging edges of dough to make a perfect rectangle.
Brush the dough with 3 tablespoons of melted butter and then sprinkle the buttered bread crumbs over ¾ of your dough, leaving the last few inches of dough uncovered.
Take your walnuts and sprinkle a 6 inch or 15 centimeter wide strip along the short end of your dough (not the end that was left uncovered with bread crumbs).
Stir together the apples, sugar, cinnamon, and raisins. You can also add a couple of tablespoons of the soaking rum, if you'd like. Stir that all together and place it over the strip of chopped walnuts.
Using your sheet, fold one long side of your strudel dough over the apples and the rest of the length of dough. Repeat the same thing on the opposite long side.
Using your sheet, roll the short side of the dough with the apples all the way up to the end of the other short side of the dough, making sure it is seam side down. Carefully transfer the strudel to a parchment-lined baking sheet, forming a horseshoe shape with the strudel. Brush melted butter over the top of the strudel.
Bake in a 400℉ / 200℃ pre-heated oven for 30-35 minutes, until golden brown and crispy on top.
Let it rest for about 30 minutes before slicing into it and serve it sprinkled with powdered sugar with a side of whipped cream, custard, or vanilla ice cream. This is best eaten the day it is made.