Roast sweet potatoes until tender, then mash with a fork or masher and let cool.
In a large bowl, mix mashed sweet potatoes, eggs, milk, melted butter or oil, sugar, and vanilla extract.
In a separate bowl, whisk together flour, baking powder, salt, cinnamon, nutmeg, and ginger.
Fold the dry ingredients into the wet until just combined. Let the batter rest for 10 minutes.
Preheat and grease your waffle maker. Pour batter and cook according to your machine's instructions until crispy and golden.
Serve warm with maple syrup, pecans, honey butter, berries, or whipped cream.