In a large mixing bowl, combine mashed potatoes, shredded cheese, beaten egg, all-purpose flour, parsley, garlic powder, salt, and pepper until the mixture is well-blended and slightly sticky.

Shape about 1/4 cup of the mixture into round patties, about 1/2 inch thick, and place them on a lined plate or baking sheet.

Heat enough vegetable oil in a skillet to cover the bottom by about 1/4 inch. Heat the oil over medium heat until it shimmers.

Carefully add a few patties to the hot oil. Fry them for 3-4 minutes until golden brown. Flip and cook for another 3-4 minutes until crispy.

Transfer cooked patties to a plate lined with paper towels to absorb excess oil. Garnish with chopped parsley if desired.