Preheat your oven to 350°F.
In a large mixing bowl, combine the ground beef, finely chopped spinach, bread crumbs, 1 ½ cups of the shredded mozzarella cheese, beaten eggs, finely chopped onion, crushed garlic, salt, and pepper. Mix everything thoroughly until the ingredients are evenly combined.
Press the meat mixture evenly into a loaf pan, making sure it's compact.
Place the loaf pan in the oven and bake for about 75 minutes, or until the internal temperature reaches 160°F.
Remove the meatloaf from the oven and sprinkle the remaining ½ cup of mozzarella cheese on top. Return it to the oven for another 5-10 minutes until the cheese is melted and bubbly.
Let the meatloaf rest for a few minutes after baking, then slice and serve.
