1. Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
2. In a large mixing bowl, combine the ground beef, chopped spinach, garlic, breadcrumbs, Parmesan cheese, egg, Italian seasoning, salt, and pepper. Mix until all ingredients are well combined, but be careful not to over-mix as this can make the meatballs tough.
3. Take a small amount of the meat mixture and flatten it in your palm. Place a cube of mozzarella in the center, then roll the meat around it to form a ball. Ensure the cheese is completely covered to prevent it from oozing out while cooking.
4. Repeat the process with the remaining meat mixture and cheese cubes.
5. Heat olive oil in a large skillet over medium heat. Add the meatballs and sear for 2-3 minutes on each side, until they are browned all over.
6. Transfer the seared meatballs to the prepared baking sheet and bake in the preheated oven for 10-12 minutes, or until cooked through.
7. Once done, let them rest for a few minutes before serving to allow the flavors to meld together.

I still remember the first time I made these for Marco. The kitchen was filled with the aroma of garlic and herbs, reminiscent of those family dinners back in Asheville. The look of delight on his face as he bit into the cheesy center was priceless!