How to Make It
Whisk together buttermilk, melted butter, and eggs in a large bowl. Whisk together flour, brown sugar, baking powder, cinnamon, baking soda, and salt in a separate large bowl. Add flour mixture to buttermilk mixture, and whisk until just smooth. Let batter stand about 5 minutes.
Preheat waffle iron to medium-high, and spray with cooking spray. Pour about 1/3 cup batter per waffle into iron, and cook until light golden browned, 3 to 4 minutes. Serve immediately.