01 - In a large bowl, thoroughly blend cold mashed potatoes, shredded cheddar cheese, green onions, garlic powder, black pepper, salt, and 1 egg until the mixture is uniform.
02 - Using heaping tablespoons, shape the mixture into balls approximately 1 1/4 inches in diameter. Arrange on a tray.
03 - Set up three bowls: one with all-purpose flour, one with beaten eggs, and one with breadcrumbs.
04 - Individually roll each formed ball in flour, dip in the beaten eggs, and then fully coat with breadcrumbs.
05 - Place the breaded balls on a tray and refrigerate for at least 20 minutes to firm up.
06 - In a deep fryer or heavy-bottomed pot, heat vegetable oil to 350°F (175°F). Use enough oil for deep frying so the balls are fully submerged.
07 - Working in batches to avoid overcrowding, fry the balls for 2 to 3 minutes per batch, turning occasionally, until golden brown and crisp.
08 - Remove the fried balls with a slotted spoon and place on paper towels to drain excess oil. Serve immediately while hot.