01 - In a large mixing bowl, blend cold mashed potatoes, cheddar cheese, finely chopped green onions, garlic powder, black pepper, salt, and one egg until mixture is uniformly incorporated.
02 - Scoop out heaping tablespoons of the mixture and roll into balls approximately 1 1/4 inches in diameter. Arrange on a tray.
03 - Set up three shallow bowls: one with all-purpose flour, one with beaten eggs, and one with breadcrumbs.
04 - Individually roll each potato ball in flour, dip into beaten eggs, and thoroughly coat with breadcrumbs.
05 - Transfer coated balls onto a tray and refrigerate for at least 20 minutes to promote structural integrity during frying.
06 - Preheat vegetable oil in a deep fryer or heavy-bottomed pot to 350°F (175°C).
07 - Fry potato balls in batches, turning as needed, until golden brown and crisp on all sides, approximately 2–3 minutes per batch.
08 - Remove fried balls with a slotted spoon and place on paper towels to drain excess oil. Serve immediately while hot.