Preheat a waffle maker.
Whisk together the milk, pumpkin puree, oil, maple syrup and egg yolks. In a separate bowl, whisk together the flours, baking powder, pumpkin pie spice, baking soda and salt.
Slowly mix the flour mixture into the pumpkin mixture and stir until smooth, taking care not to overmix.
In a separate large bowl, add the egg whites and beat with an electric mixer (or whisk vigorously by hand) until stiff peaks form, 3 to 4 minutes. Gently fold the egg whites into the batter until just combined.
Lightly spray your waffle iron with cooking spray or oil, then ladle the waffle mixture in. Cook per the manufacturer's instructions and repeat with the remaining batter. Serve with maple syrup and chopped pecans.