Combine maple syrup, ginger, and nutmeg in a pitcher. Set syrup aside.

Combine milk, pumpkin puree, egg yolks, and vanilla extract in a large bowl. Combine flour, flaxseed meal, baking soda, and salt in a separate bowl. Stir milk mixture into flour mixture. Add butter.

Beat egg whites in a clean, dry bowl until very frothy. Add brown sugar 2 tablespoons at a time and beat until soft peaks form. Fold egg whites into waffle batter in 3 additions.

Preheat a waffle iron according to manufacturer's instructions. Cook in the preheated waffle iron until waffle is golden brown and the iron stops steaming, about 5 minutes.

Serve waffles with spiced syrup.