Preheat your oven to 400°F and lightly grease a muffin tin. This helps the puffs crisp up while preventing sticking.
In a large bowl, combine mashed potatoes, cheddar cheese, eggs, milk, flour, garlic powder, salt, and black pepper. Stir until smooth and well combined.
Spoon the potato mixture into each muffin cup, filling about ¾ full. Sprinkle grated Parmesan cheese and chopped chives on top for extra flavor.
Place the muffin tin in the oven and bake for 25 minutes or until the puffs turn golden brown and crispy on the edges. Let them cool for a few minutes before removing.
Carefully remove the puffs from the muffin tin and serve warm. Enjoy them with a side of sour cream or your favorite dipping sauce. For more crispy side dishes, try these Baked Garlic Parmesan Potato Wedges.