Preheat your oven to 375°F (190°C) and prepare a baking sheet or loaf pan with nonstick spray.

In a large mixing bowl, combine ground beef, breadcrumbs, eggs, milk, onion, garlic, Worcestershire sauce, tomato paste, salt, pepper, oregano, and basil. Mix gently.

Shape half of the meat mixture into a loaf and create a trench down the center.

Fill the trench with shredded mozzarella, then cover with the remaining meat mixture.

In a small bowl, whisk together ketchup, brown sugar, and balsamic vinegar, then brush on top of the meatloaf.

Bake in the preheated oven for 50-60 minutes until the internal temperature reaches 160°F (71°C).

Remove from oven and let it rest for 10 minutes before slicing.

Slice and serve warm with your favorite sides.