In a large mixing bowl, combine the all-purpose flour, baking powder, pumpkin pie spice, and kosher salt. Whisk these dry ingredients until well-mixed.
In a separate bowl, whisk together the eggs, milk, melted unsalted butter, maple syrup, and vanilla extract until smooth.
Add the wet ingredients to the dry ingredients and whisk just until combined. Remember, it's okay if there are some lumps.
Gently fold in the mashed sweet potato puree until it's incorporated into the batter.
Preheat your waffle iron according to the manufacturer's instructions and lightly coat it with oil or butter.
Pour enough batter into the waffle iron to just cover the waffle grid.
Close the waffle maker and follow the manufacturer's instructions, usually for 5 minutes, until the waffle is golden.
Carefully remove the waffle and serve immediately with your choice of toppings, such as additional maple syrup.
Repeat with the remaining batter.