01 - In a large mixing bowl, combine cold mashed potatoes, shredded cheddar cheese, finely chopped green onions, garlic powder, black pepper, salt, and one egg. Mix thoroughly until smooth and evenly blended.
02 - Scoop heaping tablespoons of the mixture and roll each between your palms to form compact balls approximately 1 1/4 inches in diameter. Arrange on a tray as you work.
03 - Organize three separate bowls: one with all-purpose flour, another with beaten eggs, and a third containing breadcrumbs.
04 - Individually coat each potato ball by rolling first in flour, then dipping into beaten eggs, and finally rolling thoroughly in breadcrumbs until fully covered.
05 - Transfer breaded balls to a tray and refrigerate 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 to a safe depth for frying and heat to 350°F (175°C).
07 - Working in batches, gently lower chilled potato balls into the hot oil. Fry for 2-3 minutes per batch, turning to achieve an even, deep golden color and crisp exterior.
08 - Remove fried balls with a slotted spoon and drain briefly on paper towels. Serve immediately while hot.