In a large bowl, combine flour, brown sugar, baking powder, baking soda, salt, cinnamon, ginger and nutmeg.
In another bowl, whisk together milk, sweet potatoes, oil, eggs and vanilla until smooth.
Pour wet mixture into dry and stir until completely incorporated and no dry bits remain.
Preheat your waffle maker. Once hot, spray plates with oil if needed, then scoop batter onto plates, close, and cook according to manufacturer’s instructions. Keep waffles warm on a sheet pan set in a low oven while you repeat with remaining batter.
Notes
You will need 1 large or 2 medium sweet potatoes to yield 1 cup mashed. Peel and dice sweet potatoes and add to a pot, then cover with water. Boil for 15 minutes, or until tender. Drain and mash or puree.