To make apple strudel mixture: Boil water; add raisins. Remove from heat and let steep until raisins are plump and reconstituted, about 10 minutes. Drain and set aside.
In shallow pan over medium heat, add butter. Once butter melts and is bubbling, stir in brown sugar and cinnamon. Cook about 3 minutes until sugar starts to dissolve.
Add walnuts, apples, and raisins. Cook apples until just tender when pierced with fork, about 4 minutes. Set aside to cool completely.
To make batter: In large bowl, mix flours, sugar, cinnamon, baking soda, and salt. In separate bowl, beat eggs lightly and mix with buttermilk, oil, and vanilla extract.
Pour wet ingredients into dry, mixing as little as possible. Add apple strudel mixture and fold all ingredients together. Set aside.
Heat nonstick pan or griddle over medium heat. Grease pan lightly with nonstick cooking spray. Once pan is hot, ladle about 1/4 cup batter per pancake, taking care not to overcrowd pan. After 2-3 minutes, flip pancakes once.
Serve pancakes warm with syrup.