In a large bowl, combine ground beef, onion, garlic, bread crumbs, 1/2 cup of ketchup, Worcestershire sauce, salt, and pepper. Mix until well combined.
Form the meat mixture into a loaf and place it in a greased 9x13-inch baking dish.
Spread the remaining ketchup over the top of the meatloaf.
In a large pot, boil potatoes until tender. Drain and return to the pot.
Add milk and butter to the potatoes and mash until smooth. Season with salt and pepper to taste.
Spread the mashed potatoes over the meatloaf.
Sprinkle shredded cheddar cheese on top of the mashed potatoes.
Bake in the preheated oven for 45 minutes until the cheese is melted and bubbly.
Garnish with chopped parsley before serving.
Notes
This casserole can be made ahead and refrigerated until ready to bake. Just allow extra baking time if chilled.