01 - In a large mixing bowl, combine cold mashed potatoes, cheddar cheese, green onions, garlic powder, black pepper, salt, and one egg. Mix until the mixture is smooth and evenly blended.
02 - Scoop heaping tablespoons of the potato mixture and roll each portion between your hands to form balls approximately 1 1/4 inches in diameter. Arrange them on a tray.
03 - Arrange three shallow bowls: fill the first with flour, the second with the beaten eggs, and the third with breadcrumbs.
04 - Roll each potato ball first in flour, then dip into the beaten eggs, and finally coat thoroughly in breadcrumbs. Return coated balls to the tray.
05 - Transfer the prepared balls to the refrigerator and chill for at least 20 minutes to ensure they hold their shape during frying.
06 - Pour vegetable oil into a deep fryer or heavy-bottomed pot, ensuring at least 2 inches of depth. Heat the oil to 350°F.
07 - Carefully lower the chilled potato balls into the hot oil in batches. Fry, turning occasionally, until golden brown and crisp, about 2 to 3 minutes per batch.
08 - Remove fried balls with a slotted spoon and transfer to paper towels to drain. Serve hot with your choice of dipping sauce.