Preheat the oven to 350°F (175°C) and line a 9 by 5 inch loaf pan with foil or parchment paper, or grease it lightly.

In a large mixing bowl, combine 1 cup breadcrumbs and 1 packet Lipton onion soup mix until evenly distributed.

In a medium bowl, whisk together 2 large eggs and 1/2 cup whole milk until the mixture is uniform.

Pour the egg and milk mixture into the breadcrumb mixture, stir gently, and let sit for 2 to 3 minutes to hydrate.

Add 2 pounds ground beef and 1/4 cup ketchup to the bowl, then fold together gently until just combined without overmixing.

Transfer the meat mixture to the prepared loaf pan and press gently to eliminate air pockets and even out the top.

In a small bowl, whisk 1/4 cup ketchup with 2 tablespoons brown sugar and 1 tablespoon apple cider vinegar, then spread the glaze evenly over the meatloaf.

Bake in the preheated oven for 55 to 60 minutes, or until an internal temperature reaches 160°F (71°C) in the center.

Remove the meatloaf from the oven and let it rest in the pan for 5 to 10 minutes before slicing and serving.