Preheat waffle iron.
Place flour, sugar, baking powder, salt, cinnamon and pumpkin pie spice into a large mixing bowl, stir to combine.
Place egg whites into a medium mixing bowl, whisk continuously until stiff peaks form.
Place buttermilk, milk, melted butter, vanilla and egg yolks into a large bowl, whisk to combine then slowly stir into dry ingredients. Stir in pumpkin puree then gently fold in egg whites until just combined.
Scoop 1/2 cup of batter and place into center of waffle iron, close lid and let cook until golden brown and crisp, about 2 1/2 minutes depending on your waffle iron. Remove hot waffles and place on cooling rack. Continue cooking waffles until all batter is used.
To prepare buttermilk syrup, place butter, sugar and buttermilk into a small saucepan. Stir until melted and comes to a low boil. Remove from heat and stir in baking soda and vanilla. Syrup will foam up. Let sit aside and stir occasionally until foam has gone down.