In a small bowl, combine the 2/3 cup panko breadcrumbs and 1/2 cup whole milk. Stir gently and let sit for 10 minutes to allow breadcrumbs to absorb the milk.

While the binders soak, heat 1 tbsp olive oil in a skillet over medium heat. Add the finely minced onion and minced garlic, sauté for about 5 minutes until softened and translucent. Remove from heat and let cool slightly.

In a very large mixing bowl, combine the 2 lbs ground beef, soaked breadcrumb mixture, sautéed onion and garlic, 1 large egg, 1 tsp Worcestershire sauce, 1 tsp salt, 1/2 tsp black pepper, 1 tsp Italian seasoning, and 1 tbsp chopped parsley.

Use your hands to mix gently just until all ingredients are combined. Avoid overmixing to prevent a tough texture.

Line a large baking sheet with parchment paper. Lightly grease if needed. Transfer the meat mixture to the sheet and shape into a loaf about 9 inches long, 4 inches wide, and 2.5 inches high.

In a small bowl, whisk together 1/2 cup ketchup, 1/4 cup brown sugar, 1 tbsp apple cider vinegar, and 1 tsp Dijon mustard until smooth.

Preheat oven to 350°F (175°C). Place the unglazed loaf in the oven and bake for 30 minutes.

Remove the loaf from oven, brush half of the glaze evenly over the top and sides.

Return to oven and bake for another 35-45 minutes, or until internal temperature reaches 160°F (71°C). Allow carry-over cooking to reach 165°F.

Let rest on baking sheet for 10-15 minutes before slicing. Serve with remaining glaze on the side.