Preheat a waffle iron according to manufacturer's instructions.
Beat egg whites in a glass or metal bowl until soft peaks form. Lift your beater or whisk straight up: egg whites will form soft mounds rather than a sharp peak.
Beat egg yolks, buttermilk, pumpkin, and butter together with a whisk in a large bowl until smooth; add flour, brown sugar, baking powder, cinnamon, baking soda, ginger, salt, and cloves. Stir mixture with the whisk just until you have a smooth batter.
Fold egg whites into batter just until combined.
Prepare cooking surfaces of your waffle iron with cooking spray. Ladle about 2/3 cup batter into the prepared iron and cook until browned, 4 to 5 minutes.
Notes
Tips
Waffle irons come in many varieties. Consult the manufacturer directions for best guidance on batter amounts and cooking times.