How to Make It
Whisk flour, baking powder, baking soda, salt, cinnamon, ginger, and nutmeg in a medium bowl.
Make a well in the center of the dry ingredients and whisk in pumpkin, milk, brown sugar, butter and egg yolks. Using an electric mixer, beat egg whites to soft peaks; fold into pumpkin mixture until evenly combined (you can skip this step and whisk in the eggs whole, but the waffles won't be as crispy).
Heat waffle iron according to manufacturer’s instructions; brush with melted butter. Spread ½ cup batter onto iron and close; cook until waffle is golden brown and crisp, 3 to 5 minutes. Transfer to a wire rack set inside a baking sheet and place inside a warm oven. Repeat with remaining melted butter and batter.
Serve waffles with butter and maple syrup.
Waffles can be cooled and frozen in a resealable plastic bag for up to 1 month. Reheat in the toaster before serving.