01 - In a large mixing bowl, thoroughly blend cold mashed potatoes with shredded cheddar cheese, finely chopped green onions, garlic powder, pepper, salt, and one large egg until homogeneous.
02 - Portion the mixture into heaping tablespoonfuls and shape into 1 1/4-inch balls; arrange on a tray.
03 - Prepare three separate bowls: one with all-purpose flour, one with beaten eggs, and one with breadcrumbs.
04 - Coat each shaped potato ball in flour, dip into the beaten egg, and then roll in breadcrumbs to ensure an even crust.
05 - Transfer the coated balls to a tray and refrigerate for at least 20 minutes to allow them to firm up.
06 - Pour enough vegetable oil into a deep fryer or heavy-bottomed pot and heat to 350°F (175°C). Monitor temperature for consistent results.
07 - Fry the chilled potato balls in batches for 2–3 minutes, turning as needed until golden brown and crisp on all sides.
08 - Remove fried balls using a slotted spoon and set on paper towels to drain excess oil. Serve immediately while hot.