Now, let’s dive into the process of bringing these meatballs to life.

1. Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper for easy cleanup.
2. In a large mixing bowl, combine the ground beef, chopped spinach, minced garlic, breadcrumbs, beaten egg, Parmesan cheese, oregano, salt, and pepper. Mix until well combined but avoid overworking the meat.
3. Take a small portion of the meat mixture and flatten it in the palm of your hand. Place a cube of mozzarella in the center and gently wrap the meat around it, forming a ball. Repeat until all the meat mixture is used.
4. In a large skillet, heat the olive oil over medium heat. Add the meatballs and sear them on all sides until they develop a golden-brown crust, about 3-4 minutes per side.
5. Transfer the meatballs to the prepared baking sheet and bake in the preheated oven for 15-20 minutes, or until fully cooked through and the cheese is melted.