In a large bowl, stir together flour, brown sugar, baking powder, cinnamon, salt, baking soda, nutmeg, and ginger; set aside.
In a medium bowl, combine milk, pumpkin, egg yolks, butter, and, if desired, orange peel. Add pumpkin mixture all at once to flour mixture; stir just until combined (batter should be lumpy).
In a small bowl, beat egg whites with an electric mixer on high speed until stiff peaks form (tips stand straight). Gently fold beaten egg whites into pumpkin mixture, leaving a few puffs of egg white.
Heat a lightly greased waffle baker. Pour some of the batter onto the waffle grids. Close lid quickly; do not open until done. Bake according to manufacturers directions. When done, use a fork to lift waffle off grids. Repeat with remaining batter.
Serve waffles immediately or keep warm in a loosely covered ovenproof dish in a 300 degree F oven. If desired, serve with Cider-Honey Syrup. Makes 16 (4-inch) waffles.
In a small saucepan, combine apple cider or apple juice and honey. Bring to boiling; reduce heat. Simmer, uncovered, for 15 to 20 minutes or until slightly thickened. Serve warm. Cover and store any remaining syrup in the refrigerator for up to 1 week. Makes about 1 cup.