Roast or boil 2 medium sweet potatoes until fully soft, then peel, mash smooth and chill until cold. This can be done a day ahead.

Grate 1 small raw sweet potato on the large holes of a box grater. Wrap the shreds in a clean dish towel and wring out as much liquid as you can.

Whisk the flour, baking powder, garlic powder, salt and black pepper together in a large bowl.

In a second bowl, beat the eggs, then stir in the cold mashed sweet potato and the melted butter until smooth.

Fold the wet mixture into the dry, then add 1 cup of the shredded cheddar, the squeezed shreds and the sliced scallions. Stop mixing as soon as it comes together. The batter should be thick and scoopable, not pourable.

Let the batter rest for 10 minutes while the waffle iron preheats fully.

Brush the hot iron generously with neutral oil or melted butter. A spray mist is not enough for this batter.

Scatter a scant tablespoon of the held back cheddar directly onto the hot plate, then scoop about ½ cup of batter on top of it and spread it just short of the edges.

Close the lid and cook for 5 to 7 minutes without opening it. Heavy steam from the seam means the waffle is not set yet. When the steam thins to almost nothing, the waffle is done and the edges are dark gold and lacy.

Lift the waffle out and repeat, regreasing the iron before every waffle. Hold finished waffles in a 200F oven directly on the rack so the bottoms stay crisp.

Top each waffle with a fried egg, sliced scallion greens and another crack of black pepper. Add a spoonful of sour cream if you like.