In a large bowl, combine the ground beef, chopped spinach, minced garlic, egg, breadcrumbs, salt, pepper, and Italian seasoning. Mix with your hands until well blended.

Take a small handful of the meat mixture and flatten it into a patty. Place a cube of mozzarella in the center, then wrap the meat around it, forming it into a ball. Repeat until you’ve used all the meat mixture.

In a skillet, heat some olive oil over medium heat. Add the meatballs and cook them for about 5-7 minutes, turning occasionally until they’re brown and cooked through.

Serve the meatballs with a generous amount of marinara sauce ladled over them. Optionally, sprinkle more mozzarella on top.