Preheat a 12-inch skillet with cooking oil spray on medium high heat. In medium size bowl combine potatoes, ham, cheese, and garlic powder, and mix well. Divide into 4 equal patties about 1/2 inch thick. Coat patties with flour, shaking off excess. Fry patties 4-6 minutes on each side, turning only once until golden brown. Yields 4 servings.