Preheat oven to 200 degrees F°.
In a large mixing bowl, combine dry ingredients and mix well.
In a medium bowl, whisk together milk, Mashed Sweet Potatoes, eggs, and vanilla until combined. Stir sweet-potato mixture into flour mixture and melted butter until blended – some lumps may remain.
Heat a waffle iron to medium-high and lightly brush grids with melted butter. Ladle about 1/2 cup batter into center of iron (grids should be full but not overflowing), close, and cook until iron stops steaming and waffles are golden brown, about 4 minutes (or make according to waffle iron manufacturer’s instructions). Transfer waffles to wire rack in oven to keep warm.
Repeat with remaining batter. Serve with butter and maple syrup.