Whisk the flour, cocoa, sugar, and baking powder in a large bowl until combined.
Whisk ¾ cup of the sour cream, egg yolks, and 6 tablespoons of the butter in a medium bowl until combined. Stir in the flour mixture until moistened.
Beat the egg whites in a small bowl at high speed until soft peaks form. Gently fold them into the batter.
Meanwhile, heat a waffle iron until hot. Lightly grease with the remaining butter. Pour ½ cup of batter per waffle. Cook each for 3 minutes or until lightly crisp.
Serve sprinkled with powdered sugar, top with cherries, sour cream, and chocolate sauce.