In a large mixing bowl, combine mashed potatoes, cheese, flour, egg, green onions, garlic powder, salt, and pepper.
Mix until all ingredients are well incorporated and form a cohesive mixture.
Divide the mixture into equal portions and shape into patties.
Heat vegetable oil in a large skillet over medium heat.
Cook patties in the skillet for 3-4 minutes on each side, or until golden brown and crispy.
Transfer to a paper towel-lined plate to drain excess oil before serving.