Separate eggs with whites in one bowl and yolks in another.
In a large bowl, mix flour, brown sugar, baking powder, cinnamon, allspice, nutmeg, and salt.
2 1/2 cups flour, 1/2 cup brown sugar, 1 1/2 tablespoons baking powder, 1 tablespoon cinnamon, 1 teaspoon allspice, 1 teaspoon nutmeg, 1/2 teaspoon salt
In a separate bowl, mix together the milk, pumpkin, ginger, and egg yolks until completely blended. Slowly add melted butter while whisking.
2 cups milk, 1 cup canned pumpkin, 1 teaspoon fresh ginger, 4 eggs, 1/4 cup unsalted butter
Add liquid ingredients (less egg whites) to dry ingredients and mix until just combined.
Place egg whites in a clean metal or glass bowl. Whip until medium peaks form.
Add 1/3 of the egg whites to the batter and stir gently. Add the remaining egg whites, folding them in as gently as possible and using as few motions as possible until no white streaks remain.
Pour batter into your waffle maker. Let the waffles cook until the timer goes off, using a fork to gently pry the waffles out, if needed.
Serve immediately. Store any leftovers in a tightly sealed container, and pop in the toaster the next day.