Grease and preheat the waffle iron according to the manufacturer's instructions. Preheat the oven to200℉ (95℃).
Place 2 cups of rolled oats into the blender with 2 teaspoons baking powder, 1 teaspoon baking soda, ½ teaspoon salt, 1 teaspoon cinnamon, ½ teaspoon nutmeg, and ¼ teaspoon ginger. Pulse until the ingredients are nice and combined together. Pour out this mixture into a mixing bowl and set aside.
Place 1-¼ cups buttermilk, 2 eggs, 2 cups sweet potato puree (or flesh of sweet potatoes) and 1 teaspoon vanilla extract in the blender. Blend until smooth. Add the flour/oat mixture on top of the wet ingredients and blend again until smooth and combined. If your batter is too thick, add up to 3 tablespoons of additional buttermilk. *By placing the wet ingredients on the bottom of the blender, the batter will come together much easier.
Ladle ⅓- ½ cup of the batter unto each waffle iron (use the amount directed per your waffle maker) and cook until golden on both sides.
Remove the cooked waffles from the waffle iron, place them onto a baking rack on a sheet pan, and keep warm in a 200℉ (95℃) oven until serving. Repeat until the batter is gone, greasing the waffle iron in between each batch.
Serve with toasted walnuts, maple syrup, and whipped cream if desired.
Notes
Oats: You can use old-fashioned regular oats or quick-cooking oats for these sweet potato waffles. Do NOT use steel-cut oats.Sweet Potato Puree: You can opt to use canned or homemade sweet potato puree or the flesh of 2 large or 3 medium leftover baked sweet potatoes. Buttermilk: To make homemade buttermilk, combine 1-½ teaspoons lemon juice or apple cider vinegar with 1-¼ cup of any variety of non-dairy or regular milk and let sit for 5 minutes before using. 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. To Bake Sweet Potatoes for Sweet Potato Puree: Preheat the oven to 400 degrees F. Pierce 2-3 sweet potatoes with a fork several times then place them on a sheet pan lined with foil. Bake the potatoes until fork tender, about 40-50 minutes. Once baked, let cool slightly, remove skins and blend or mash the flesh of the potatoes with a fork until smooth. Alternatively, use my instructions for Instant Pot Sweet Potatoes.