01 - Bring a large pot of salted water to a boil. Add potatoes and cook for 15-18 minutes until fork-tender.
02 - Drain potatoes well and return to pot. Mash until smooth.
03 - Stir in butter and milk until fully incorporated. Season with garlic powder, onion powder, smoked paprika, salt, and pepper. Cool for 10 minutes.
04 - Add egg to cooled mashed potatoes and mix thoroughly.
05 - Transfer mixture to piping bag fitted with large star tip, or shape by hand into fry-like sticks.
06 - For baking: Preheat oven to 425°F. Line baking sheet with parchment paper. Pipe or arrange potato sticks on sheet. Lightly brush with oil. Bake for 20-25 minutes, turning halfway, until golden and crisp. For frying: Heat oil to 350°F. Carefully lower fries in batches. Fry for 2-3 minutes until golden and crispy. Drain on paper towels.
07 - Serve hot, garnished with parsley or Parmesan if desired.