Preheat your oven to 350°F (175°C) and prepare your muffin tin by greasing it lightly or lining with muffin liners.

Boil peeled potatoes until fork-tender, then mash until smooth. Allow to cool.

In a large mixing bowl, whisk together eggs, sour cream, and melted butter until creamy.

Add cooled mashed potatoes to the wet mixture and stir until blended. Fold in cheddar cheese.

Mix in garlic powder, onion powder, salt, and black pepper. Fold in green onions if using.

Spoon the mixture into the muffin tin, filling each cup about three-quarters full.

Sprinkle grated Parmesan cheese on top of each muffin.

Bake for 25–30 minutes until tops are golden brown and a toothpick inserted comes out clean.

Allow muffins to cool for 5 minutes before transferring to a wire rack.