Preheat your oven to 350°F (175°C). Grease a muffin tin and set aside.
In a large mixing bowl, combine ground beef, breadcrumbs, milk, ketchup, chopped onion, egg, garlic powder, Italian seasoning, salt, and pepper. Mix until well combined.
Spoon the meat mixture evenly into the muffin tin, filling each cup about two-thirds full.
Bake in the preheated oven for 20-25 minutes, or until the internal temperature reaches 160°F (70°C). Remove from the oven and allow to cool slightly.
While the meatloaf muffins are baking, prepare the mashed potatoes. Boil the cubed potatoes in salted water until tender, about 15-20 minutes.
Drain the potatoes and return them to the pot. Add milk, butter, salt, and pepper. Mash until smooth and creamy.
Once the meatloaf muffins have cooled slightly, use a piping bag or a spoon to top each muffin with the mashed potatoes, creating a 'frosting' effect.
Serve warm and enjoy!