01 - In a large mixing bowl, thoroughly combine cold mashed potatoes, shredded cheddar cheese, green onions, garlic powder, black pepper, salt, and one egg until the mixture is homogenous.
02 - Portion heaping tablespoons of the mixture and shape into balls approximately 1 1/4 inches in diameter. Arrange on a tray.
03 - Organize three bowls: one with flour, one with beaten eggs, and one with breadcrumbs.
04 - Roll each potato ball in flour, dip in beaten eggs, then coat evenly with breadcrumbs.
05 - Place the coated balls on a tray and refrigerate for a minimum of 20 minutes to ensure they hold their shape when frying.
06 - Preheat oil in a deep fryer or heavy-bottomed pot to 350°F (175°C).
07 - Working in batches, fry the potato balls, turning occasionally, until crisp and golden brown, about 2 to 3 minutes per batch.
08 - Remove the fried balls using a slotted spoon and drain on paper towels. Serve while hot with preferred dipping sauces.