How to Make It
Preheat oven to 200°F. Stir together eggs, mashed potatoes, flour, butter, salt, pepper, and garlic powder in a medium bowl. Fold in cheese and scallions until just combined.
Heat a large nonstick skillet over medium-high. Add 2 tablespoons of the oil to skillet; swirl to coat. Once oil shimmers, spoon 4 mounds (about 1/4 cup each) batter onto skillet, flattening each with a spatula to about 1/4-inch thick. Cook until golden brown and crispy, 2 to 3 minutes per side. Transfer potato pancakes to a wire rack set inside a baking sheet, and place in preheated oven to keep warm. Repeat process twice with remaining oil and batter.
To serve, dollop sour cream evenly onto warm potato pancakes; sprinkle with chives.