How to Make It
In a mixing bowl, whisk together flour, sugar, baking soda, salt, cinnamon, and nutmeg until well combined.
In a separate bowl, whisk together buttermilk, eggs, melted butter, and sweet potato. Add to dry ingredients and stir together until no pockets of flour remain. Use immediately or refrigerate until ready to use.
Preheat waffle iron. Spray waffle iron with cooking spray, add waffle batter, and cook until the outsides of the waffles are lightly browned and cooked through. Serve with butter and maple syrup or apple butter, if desired.
To make the mashed sweet potato, wrap sweet potatoes in aluminum foil and roast in a 425°F oven for 1 1/2 hours. Turn off the oven and allow the sweet potatoes to cool in the oven for 2 hours. This allows more of the starches in the sweet potato to transform into complex sugars, making the sweet potato flesh both sweeter and softer. Peel and mash the sweet potatoes.