- Preheat your oven to 400°F. Line a baking sheet with parchment paper and lightly grease it with cooking spray or oil. 
- In a large mixing bowl, combine the cooled mashed potatoes, cheddar cheese, Parmesan cheese, flour, eggs, garlic powder, onion powder, salt, black pepper, and chives (if using). Mix until well combined. 
- Using a spoon or your hands, form the mixture into small balls, about 1 to 1.5 inches in diameter. Roll each ball in breadcrumbs to coat evenly. 
- Place the coated potato puffs on the prepared baking sheet, leaving some space between each puff. 
- Bake in the preheated oven for 20-25 minutes, or until the puffs are golden brown and crispy on the outside. 
- Remove from the oven and let cool for a few minutes before serving.