Heat a waffle iron according to the manufacturer's directions.
Whisk together the flours, baking powder, baking soda, salt, and sugar in a medium bowl.
Whisk the eggs and butter together in another bowl, and then whisk in the buttermilk.
Add the wet ingredients to the dry and whisk to combine. Rest the batter for 5 minutes.
Lightly coat the waffle iron with nonstick spray. Ladle the recommended amount of waffle batter onto the iron according to the manufacturer's recommendations. Close the iron top and cook until the waffle is golden on both sides and is easily removed from the iron. Serve immediately or keep warm in a 200ºF oven until ready to serve.