01 - In a large mixing bowl, thoroughly blend cold mashed potatoes, shredded cheddar cheese, chopped green onions, garlic powder, black pepper, salt, and one large egg until the mixture is evenly distributed.
02 - Scoop heaping tablespoons of the mixture and roll each into a ball roughly 1 1/4 inches in diameter. Arrange them in a single layer on a tray.
03 - Set up three separate bowls: one with all-purpose flour, one with beaten eggs, and one with breadcrumbs.
04 - Coat each formed potato ball first in flour, then dip into the beaten eggs, followed by rolling in breadcrumbs until evenly coated.
05 - Transfer coated balls to a tray and refrigerate for at least 20 minutes to help them firm up before frying.
06 - In a deep fryer or heavy-bottomed pot, heat vegetable oil to 350°F (175°C).
07 - Fry the balls in batches, turning occasionally, for 2 to 3 minutes per batch or until the crust is golden brown and crisp.
08 - Remove fried balls using a slotted spoon and drain on paper towels. Serve immediately while hot.