Grease and preheat the waffle iron according to manufacturer instructions.
Place the oats or flour into the blender with the baking powder, baking soda, salt, cinnamon, nutmeg, and ginger. Pulse until the ingredients are nice and combined together. If using oats, process until slightly broken down. Pour out this mixture into a mixing bowl and set aside.
Place the milk, eggs, sweet potato puree, and vanilla extract in the blender. Add the flour/oat mixture on top of the wet ingredients. By placing the wet ingredients on the bottom of the blender, the batter will come together much easier. Blend until the batter is smooth and all the ingredients evenly incorporated. This is a thicker batter. However, if too thick, add up to 3 tablespoons of additional milk.
Ladle ⅓ cup of mixture unto each waffle iron mold and cook until golden on both sides. Repeat until the batter is gone, greasing the waffle iron in between each batch.
Serve with toasted walnuts and maple syrup if desired.
Oats: You can use old-fashioned regular oats or quick cooking oats for these sweet potato waffles. Do NOT use steel-cut oats.Flour: In place of the oats, use 2 cups of all-purpose flour.Sweet Potato Puree: Instead of sweet potato puree, you can use canned 100% pumpkin puree.Milk: Any variety of milk works well in this easy waffle recipe. Use coconut milk or almond milk to keep this recipe dairy-free.Storage: Store leftover cooled waffles in an airtight container in the refrigerator for up to 4 days. Alternatively, freeze for up to 3 months. Toast in a toaster or toaster oven to reheat.