In a mixing bowl, combine the leftover mashed potatoes, shredded cheese, beaten egg, flour, garlic powder, onion powder, black pepper, and salt. Mix until well combined.

Chill the mixture in the refrigerator for about 10 minutes to make it easier to handle.

Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.

Using your hands, form the potato mixture into small balls or puffs, about 1 inch in diameter.

Roll each puff in the bread crumbs mixed with Parmesan cheese until fully coated.

Place the coated puffs on the prepared baking sheet, spacing them about 2 inches apart.

Bake in the preheated oven for 15-20 minutes, or until golden brown and crispy.

Remove from the oven and let cool slightly before serving.