01 - In a large bowl, mix cold mashed potatoes, cheddar cheese, green onions, garlic powder, black pepper, salt, and one egg until thoroughly incorporated.
02 - Portion heaping tablespoons of the mixture and roll firmly into balls approximately 1 1/4 inches in diameter. Arrange on a tray.
03 - Set up three separate 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 generously in breadcrumbs. Ensure each ball is fully covered.
05 - Place breaded balls on a tray and refrigerate for at least 20 minutes to help maintain their shape during frying.
06 - Fill a deep fryer or heavy-bottomed pot with vegetable oil and heat to 350°F.
07 - Working in batches, fry the chilled balls for 2 to 3 minutes each, turning as needed, until they are golden and crisp.
08 - Transfer the fried balls to a plate lined with paper towels to drain excess oil. Serve hot.