Preheat the oven to 375°F. In a mixing bowl, combine the ground beef, breadcrumbs, egg, onion, garlic, Worcestershire sauce, salt, and black pepper. Mix until evenly blended.
Divide the mixture into four equal portions and shape each into a small loaf. Place the loaves on a baking sheet lined with parchment paper.
Bake the meatloaves for 20 minutes. While they bake, place the potatoes in a pot, cover with water, and bring to a boil. Cook until the potatoes are tender, about 15 minutes.
Drain the potatoes and return them to the pot. Add the milk, butter, and salt. Mash until smooth.
Remove the meatloaves from the oven. Spoon the mashed potatoes evenly over each loaf, spreading to cover the top.
Return the topped meatloaves to the oven for 10 more minutes, until the potato topping begins to set.
Sprinkle with chopped parsley before serving.