Preheat waffle iron. In a small saucepan, melt the butter over medium-low heat and continue to cook, swirling occasionally, until butter turns golden brown, Skim foam from top, and remove from heat. Pour into a bowl to stop the cooking, leaving any burned sediment behind; let cool.
In a medium bowl, whisk together flour, brown sugar, baking powder, soda, salt, and spices.
In a large bowl, whisk together eggs, buttermilk, vanilla, pumpkin, and browned butter. Whisk in dry ingredients just until smooth.
Spray hot waffle iron with cooking spray and spoon batter into waffle iron, spreading quickly. Cook according to manufacturer’s instructions. Continue making waffles until batter is gone. Keep waffles warm in a 250 degree F oven. Serve warm with Brown Butter Buttermilk Syrup, if desired.
Note-these waffles freeze well. Cool completely and put in a freezer bag! Pop them in the toaster to reheat!