Set your oven to 375°F (190°C) and grease a 9x9-inch baking dish lightly.
Spread the mashed potatoes evenly across the bottom of the dish and season with salt and pepper to your liking.
Arrange the cooked meatballs evenly over the layer of mashed potatoes.
Pour the brown gravy evenly on top, ensuring everything is nicely coated.
Sprinkle the shredded cheese over the gravy-covered meatballs and potatoes.
Bake uncovered for about 20 to 25 minutes until everything is heated through and the cheese has melted and is bubbling.
Once baked, garnish with chopped parsley or green onions if you like, then serve warm for a cozy and satisfying meal.