Preheat your oven to 350°F (175°C).

Sauté the chopped onion in a skillet over medium heat until soft and translucent, about 5 minutes.

In a large bowl, combine ground beef, breadcrumbs, eggs, ketchup, Worcestershire sauce, sautéed onions, salt, pepper, and garlic powder. Mix until just combined.

Grease a muffin tin and fill each cup three-quarters full with the meat mixture.

Bake for 20-25 minutes or until golden brown and cooked through.

While cooling slightly, prepare mashed potatoes and mix in shredded cheddar and seasonings.

Pipe the mashed potato frosting onto each meatloaf cupcake.