Step 1: Preheat your oven to 375°F (190°C). Grease a 12-cup muffin tin well.
Step 2: In a large bowl, combine the ground beef, breadcrumbs, beaten egg, milk, diced onion, minced garlic, 1/4 cup ketchup, Worcestershire sauce, dried thyme, dried oregano, salt, and black pepper.
Step 3: Mix gently with your hands until just combined. Be careful not to overmix, as this can make the meatloaf tough.
Step 4: Divide the meatloaf mixture evenly among the 12 muffin cups. You can shape them slightly to resemble cupcakes. If desired, spread a thin layer of extra ketchup on top of each meatloaf before baking.
Step 5: Bake for 20-25 minutes, or until cooked through and an internal temperature of 160°F (71°C) is reached. Remove from oven and let rest in the muffin tin for 5 minutes.
Step 6: While the meatloaf bakes, prepare the potato topping. Place the peeled and quartered potatoes in a large pot and cover with cold, salted water. Bring to a boil and cook until fork-tender, about 15-20 minutes.
Step 7: Drain the potatoes thoroughly. Return them to the hot pot and mash them until smooth.
Step 8: Add the warmed milk or cream, butter, salt, pepper, and optional garlic powder to the mashed potatoes. Whip until light and fluffy.
Step 9: Carefully remove the meatloaf cupcakes from the muffin tin and transfer them to a wire rack set over a baking sheet (this helps catch any potato drips if broiling).
Step 10: Using a piping bag with a star tip (or a spoon), pipe or dollop the whipped potato topping generously onto each meatloaf cupcake, creating a "frosting" effect.
Step 11: (Optional) For a golden topping, you can briefly broil the finished cupcakes for 1-2 minutes, watching carefully to prevent burning. Garnish with fresh chives if desired. Serve hot.