Preheat the oven to 375°F (190°C) and line a rimmed baking sheet with aluminum foil or lightly grease a 9x5 inch loaf pan.

In a large bowl, combine the ground beef, breadcrumbs, 1/2 cup milk, eggs, onion, garlic, salt, black pepper, and parsley. Mix gently with your hands just until combined.

Shape the meat mixture into a loaf on the prepared baking sheet or press evenly into the loaf pan.

In a small bowl, whisk together the ketchup, brown sugar, and apple cider vinegar to make the glaze. Spread this mixture evenly over the top of the loaf.

Bake for 55 to 65 minutes, or until an instant-read thermometer inserted into the center reaches 160°F.

While the meat bakes, place the cubed potatoes in a large pot of salted water. Bring to a boil and cook for 15-20 minutes until tender. Drain well, then return to the pot and mash with the butter and remaining 1/2 cup of milk until smooth.

Steam the green beans in a steamer basket over boiling water for 5 to 7 minutes until tender-crisp. Season with a pinch of salt and pepper.

Remove the meat from the oven and let it rest for 10 minutes before slicing. Serve hot with the mashed potatoes and steamed green beans.