Preheat the oven to 425 degrees F. Pierce the sweet potatoes all overwith a fork and microwave until tender, about 15 minutes.
Meanwhile, coat a rimmed baking sheet with cooking spray. Combine the turkey, onion, panko and egg in a bowl. Add half each of the ketchup, hoisin sauce and ginger and season with salt and pepper. Mix with your hands until just combined. Form into a 9-by-11-inch rectangle on the prepared baking sheet. Mix the remaining ketchup, hoisin sauce and ginger in a small bowl with 2 tablespoons water; brush over the meat. Bake until golden and cooked through, 12 to 15 minutes. Turn on the broiler and broil until the glaze is just caramelized, 1 to 2 minutes.
Mix the butter, half of the scallions, 1/2 teaspoon salt, and pepper to taste in a small bowl. Split the potatoes and top with the scallion butter. Slice the meatloaf and serve with the potatoes. Sprinkle with the remaining scallions.
Photograph by Justin Walker
Courtesy of Food Network Magazine