Sift first 3 ingredients into bowl. Add egg and 1/4 cup butter, melted. Then add 1/2 cup ice water. Stir until blended, then knead to smooth ball on lightly floured board. Cover with towel and let rest at least 1/2 hour. Saute crumbs in 2 TB butter until lightly toasted, add nuts and set aside. Peel and core apples, cut in wedges, then in thin crosswise slices.
Mix with next 4 ingredients. On lightly floured board, roll dough to a 24x16 inch rectangle. Brush with 2 TB butter, melted. Sprinkle with crumb mixture to within 1 inch of edges. Spread evenly with apple mixture. Then roll from long side as for jelly roll and seal ends. Shape in horseshoe and put seam down, on greased baking sheet. Melt 1/4 c butter and brush some on strudel. Bake in hot oven 400 about 40 minutes. Brush occasionally with remaining butter. Serve warm in slices.