Preheat your oven to 350°F (175°C) and prepare a baking pan by lining it with aluminum foil and lightly greasing it.

Melt 2 tablespoons of butter in a medium skillet over medium heat. Add the chopped onion and sauté for about 5 minutes until translucent.

In a large mixing bowl, whisk together 2 eggs, ½ cup of milk, and 1 cup of Italian breadcrumbs. Let it sit for 5-10 minutes.

Combine the soaked breadcrumb mixture with 1 pound of lean ground beef, the sautéed onions, ½ cup of ketchup, 1 tablespoon of Italian seasoning, ¼ cup of chopped parsley, and season with salt and pepper.

Transfer the mixture into the baking pan and shape into a loaf, about 8 inches long, with a slight indentation on top.

Bake the meatloaf in the preheated oven for approximately 40 minutes until firm and the internal temperature reaches 160°F (70°C).

While baking, mix ½ cup of ketchup and 2 tablespoons of brown sugar for the topping.

Spread the topping over the meatloaf after 40 minutes and bake for an additional 15-30 minutes until bubbling and caramelized.

Once baked, let the meatloaf rest for at least 10 minutes before slicing and serving.