In a large mixing bowl, combine the breadcrumbs and milk and let them soak for about 5 minutes to soften. Then, add the ground beef, egg, grated Parmesan cheese, minced garlic, Italian seasoning, salt, black pepper, and chopped parsley. Mix gently with your hands until just combined; avoid overmixing to keep the meatballs tender and juicy.

With your hands, shape the mixture into golf ball-sized meatballs—aim for about 24 in total. As you form each meatball, press gently in the center to create a slightly larger indent for the mozzarella eyepieces later.

Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper, then place the meatballs on it. Bake in the preheated oven for 20-25 minutes until they are cooked through and golden-brown.

While the meatballs bake, dry the mozzarella balls with a paper towel. Using a small knife, carefully slice the green olives in half to create pupils. Attach each half onto a mozzarella ball to create the spooky eyeballs.

In a large skillet, pour in the marinara sauce and bring it to a gentle simmer over medium heat. Once warm, add the baked meatballs and simmer for about 5 minutes, turning occasionally to coat evenly.

Once warmed, gently press a mozzarella eyeball onto each meatball while still hot. Use toothpicks dipped in red gel food coloring to create creepy veins. Serve on a festive platter with extra marinara sauce.