In medium bowl mix together mashed potatoes, flour, Pepper Jack cheese, egg, green onions, parsley, onion powder, garlic powder, salt, pepper and baking powder.
Heat 1 tablespoon canola oil in skillet over medium heat. Using large cookie scoop place 3-4 scoops into skillet. Spray spatula with nonstick cooking spray and press to flatten. Shake the spatula just a touch to loosen potato cake back into pan. Cook until golden brown on each side.