Prepare the potatoes by peeling and cubing them.
Boil the potatoes in salted water until fork-tender.
Drain the potatoes and return them to the pot.
Add butter, sour cream, garlic powder, salt, and pepper to the pot.
Mix in shredded cheese and chopped green onions.
In a separate bowl, combine the cooked meat with additional seasoning if desired.
Preheat the oven to 375°F (190°C).
Spoon half the mashed potatoes into a greased baking dish and create a well in the center.
Fill the well with the meat mixture, then top with the remaining mashed potatoes.
Sprinkle additional cheese on top and bake for 25-30 minutes.
Let cool briefly before serving.