Preheat the oven to 400°F (200°C) so it’s fully heated before baking. Line or grease your baking sheet to prevent sticking. Preparing this first ensures the bites cook evenly.
Combine mashed potatoes, cheddar, Parmesan, sour cream, green onions, garlic powder, seasoning, and egg in a large bowl. Stir until evenly mixed but avoid overmixing. The mixture should be thick and easy to scoop.
Use a spoon or cookie scoop to portion small balls of the mixture. Place them on the baking sheet with space between each. Uniform sizes help them cook evenly.
Roll each portion lightly in panko breadcrumbs to coat. This outer layer gives the bites their signature crunch. Return them to the tray after coating.
Lightly spray or brush the tops with oil for better browning. Bake for 20–25 minutes until crisp and golden outside while soft and cheesy inside.