Bring a medium saucepan of lightly salted water to a boil. Add sweet potatoes and cook until tender but still a bit firm, about 15 minutes. Drain, then immediately immerse in cold water to loosen skins. Drain again; remove and discard skins.
Sift flour, baking powder, salt, and nutmeg together into a medium bowl.
Chop sweet potatoes, transfer to another medium bowl, and mash. Mix in milk, melted butter, and egg. Gradually mix in flour mixture until well combined.
Lightly grease a griddle and preheat over medium-high heat.
Working in batches, drop heaping tablespoonfuls batter onto the hot griddle and cook until the surface begins to bubble, 3 to 4 minutes. Flip and cook on the other side until golden brown, 2 to 3 more minutes.