Preheat oven to 350°F. Generously butter and flour a 12-cup Bundt pan; use a pastry brush to get into all the crevices.
In a large bowl, whisk together both flours, baking powder, 1 teaspoon cinnamon, baking soda, and salt.
In another bowl, whisk together 1 ½ cups sugar, cider, oil, applesauce, vanilla, and eggs.
Add egg mixture to flour mixture; whisk until combined. Transfer batter to prepared pan.
Bake, rotating pan halfway through, until a tester inserted in center comes out clean, 45 to 50 minutes.
Transfer pan to a wire rack set over a rimmed baking sheet; let cool 15 minutes. Meanwhile, mix together remaining ¼ cup sugar and ½ teaspoon cinnamon.
Invert warm cake onto rack. Brush with melted butter, then sprinkle liberally with cinnamon sugar. Let cool completely before serving.
