01 - In a large mixing bowl, combine cold mashed potatoes, shredded cheddar cheese, chopped green onions, garlic powder, black pepper, salt, and one egg. Mix until the ingredients are evenly incorporated.
02 - Scoop heaping tablespoons of the potato mixture and roll between your palms to create balls approximately 1 1/4 inches in diameter. Arrange them evenly on a tray.
03 - Arrange three separate bowls: place flour in the first, beaten eggs in the second, and breadcrumbs in the third.
04 - Roll each ball in flour to coat, dip into the beaten eggs, then dredge thoroughly in breadcrumbs. Ensure each ball is evenly coated at every stage.
05 - Transfer coated balls onto a tray and refrigerate for at least 20 minutes to firm up their shape.
06 - Pour vegetable oil into a deep fryer or heavy-bottomed pot and heat to 350°F (175°C).
07 - Carefully lower prepared balls into hot oil in batches. Fry for 2–3 minutes, rotating occasionally, until golden brown and crisp.
08 - Remove fried balls with a slotted spoon and set on paper towels to drain excess oil. Serve hot.