Preheat your oven to 375°F (190°C).
In a large bowl, combine ground beef, breadcrumbs, egg, garlic powder, onion powder, salt, and pepper.
Transfer the meat mixture to a greased baking dish and shape it into a loaf.
In a separate bowl, mix together the mashed potatoes, sour cream, and half of the cheddar cheese.
Spread the potato mixture evenly over the meatloaf layer in the baking dish.
Sprinkle the remaining cheddar cheese on top of the mashed potatoes.
Bake in the preheated oven for 40-45 minutes, or until the meatloaf is cooked through.
Remove from oven and let it rest for 10 minutes before slicing.
Garnish with chopped green onions before serving.
